Exposure apparatus

ABSTRACT

Two independent fine adjustment stages ( 62, 72 ) are arranged on one coarse adjustment stage ( 73 ) to simultaneously perform all of focus measurement and part of alignment measurement in parallel with exposure operation. A method of transporting a wafer together with a chuck is adopted as a precondition. Alignment of a pattern on a wafer ( 60 ) with a chuck ( 61 ) is performed before the chuck is mounted on each fine adjustment stage.

FIELD OF THE INVENTION

[0001] The present invention relates to an exposure technique for use ina lithography process in the manufacture of a semiconductor device.

BACKGROUND OF THE INVENTION

[0002]FIG. 2A shows a typical arrangement of a conventional exposureapparatus.

[0003] In FIG. 2A, reference numeral 1 denotes a reticle; 2, a reticlestage for scanning the reticle 1; 3, a reticle stage guide of thereticle stage 2; 4, a projection system; 5, an alignment scope formeasuring pattern positions; 6 and 7, focus detection systems(light-projecting and light-receiving units) of a focus measurementsystem for measuring the position of a wafer upper surface; 8, a wafer;9, a chuck for holding the wafer; 10, a fine adjustment stage which canfinely drive in the X, Y, Z, and θ (this represents rotation in adirection parallel to the X-Y plane (i.e., rotation about the Z-axis)hereinafter) directions and in the tilt (this represents a tilt withrespect to the X-Y plane hereinafter) direction; 11, a coarse adjustmentstage which can drive the fine adjustment stage 10 in the X and Ydirections; and 12, a wafer stage surface plate of the coarse adjustmentstage 11.

[0004] In the conventional semiconductor exposure apparatus, thealignment scope 5 arranged adjacent to and at a distance BL from theprojection system 4 measures the position of a pattern on the wafer 8.Then, the wafer 8 is fed by the coarse adjustment stage 11 to below theprojection system 4. The reticle 1 and wafer 8 undergo scan operationrelative to the projection system 4 at a velocity of the magnificationratio of the projection system 4 such that a pattern on the reticle 1 istransferred onto a predetermined position on the wafer 8.

[0005] In the above-mentioned transfer, the focus measurement systemmeasures the position of the upper surface of the wafer, and exposureoperation is performed while the fine adjustment stage 10 performssequential alignment in the focus direction such that the position ofthe upper surface of the wafer coincides with that of the image plane ofthe projection system 4.

[0006] The conventional semiconductor exposure apparatus has thefollowing problems.

[0007] (1) Increase in Throughput

[0008] The conventional semiconductor exposure apparatus needs tomeasure the position of a pattern on the wafer 8 below the alignmentscope 5 before exposure operation. This is one of the major factorswhich limit the throughput of the apparatus.

[0009] (2) Enhancement of Ease in Increasing Measurement Precision ofFocus Detection System

[0010] The conventional semiconductor exposure apparatus needs toarrange the focus measurement system for the wafer below the projectionsystem 4, as described above. For this reason, it is becoming difficultin terms of the mounting space to, e.g., implement a multichanneldetection system or improve a detection optical system to increase themeasurement precision of the focus measurement system.

[0011] (3) Relaxation of Constraints on Design of Projection System

[0012] In designing the projection system 4, the above-mentioned focusmeasurement system is arranged below the projection system and thus alarge back focal distance is necessary. This imposes considerableconstraints on the design of the projection system 4. Along with arecent increase in NA of the projection system 4, this problem hasbecome serious. The problem will become serious in a mirror projectionsystem of a future EUV exposure apparatus as well.

[0013] (4) Facilitation of Cleaning Below Projection System

[0014] Recently, contamination from a resist has been perceived as aproblem. To prevent this, a jet of clean air is provided below theprojection system 4. However, the focus measurement system describedabove is also arranged below the projection system 4, and thus it isdifficult to form a complete laminar flow of clean air.

[0015] (5) Facilitation of Chuck Cleaning

[0016] As future exposure apparatuses, semiconductor exposureapparatuses using an F₂ excimer laser or EUV light are being developed.In these semiconductor exposure apparatuses, the atmosphere for exposurelight must be purged with nitrogen or must be evacuated to a vacuum. Asemiconductor exposure apparatus used in such an environment needs toperiodically extract a wafer chuck to the outer air side for cleaning. Aconventional exposure apparatus, however, has no chuck transportfunction required for this operation.

[0017] To solve some problems of a conventional exposure apparatus, thefollowing two methods are proposed. Their outlines will be describedbelow.

[0018] (A) Place Two Coarse Adjustment Stages on Same Surface Plate

[0019]FIG. 2B shows the arrangement of improved method 1 in aconventional semiconductor exposure apparatus. Reference numeral 20denotes an exposure wafer; 21, an exposure chuck; 22, an exposure fineadjustment stage; 23, an exposure coarse adjustment stage; 30, ameasurement wafer; 31, a measurement chuck; 32, a measurement fineadjustment stage; and 33, a measurement coarse adjustment stage.

[0020] The semiconductor exposure apparatus according to improved method1 has the two coarse adjustment stages, two fine adjustment stages, andthe like. Exposure operation and measurement operations (alignment andfocus measurements) can simultaneously and independently be performedfor the wafers on the fine adjustment stages at exposure and measurementpositions.

[0021] When predetermined processes end at the exposure and measurementpositions, the fine adjustment stages are separated from the coarseadjustment stages and are interchanged. The wafer having undergonemeasurement operation is moved to the exposure position for the exposureoperation. Reference marks (not shown) are formed on the edges of thewafer chucks and are measured at the measurement and exposure positions.With this operation, measurement results (alignment and focusmeasurement results) at the measurement position are accuratelyreflected in exposure, and accurate alignment and focus are implementedat the exposure position.

[0022] Method 1 has advantages and disadvantages as follows.

[0023] (Advantages)

[0024] Exposure and measurement operations can be performed in parallel.If the time for the measurement operation is equal to or shorter thanthe time for the exposure operation, the measurement operation does notcause a decrease in throughput. Since enough time can be spared for themeasurement operation, multipoint measurement or the like can beperformed, and an increase in precision can be expected. Additionally,since a projection system and an alignment/focus measurement system arespaced apart from each other, constraints on the design of theprojection system can be relaxed. Cleaning below the projection systemis also facilitated.

[0025] (Disadvantages)

[0026] Independent operation of the two fine adjustment stages and twocoarse adjustment stages increases the size of the entire stage and thecomplexity of a mechanism which interchanges the two fine adjustmentstages. It is difficult to ensure a long-term reliability and performreplacement in a short time. Also, since the two stages operateindependently of each other on one surface plate, their reaction forcesmake it difficult to keep the precision of scan synchronization betweena reticle and wafers high at a high stage speed. Additionally, eachstage basically has only a wafer transport function and requiresconsiderable alterations to add the chuck unloading function describedabove.

[0027] Typical known examples of improved method 1 include PCT(WO)2000-505958.

[0028] This known example discloses use of a counter mass to reduceeffects of reaction forces generated by the independent operation of thetwo stages. Only one counter mass is used for the two stages, and it isdifficult to completely remove the effects of the reaction forces.

[0029] As an example similar to the method in FIG. 2B, there isavailable Japanese Patent Laid-Open No. 10-163098.

[0030] As in the above-mentioned known example, this known example hastwo stages capable of independent operation. The example proposessynchronization between the two stages in a specific operation forpreventing any mutual interference between them and a reduction in sizeof the apparatus. This case may avoid any interference between the twostages and reduce the size of the apparatus. However, processing on onestage may be made to wait due to synchronization between the two stages,and a trade-off relationship is established between a reduction in sizeand an increase in throughput. Also, in this known example as well, theabove-mentioned reaction force problem still remains unsolved.

[0031] As another example similar to the method in FIG. 2B, there isavailable Japanese Patent No. 3,045,947.

[0032] This known example is directed to a stepper. Similarly to theabove-mentioned known example, the example has two stages capable ofindependent operation and proposes parallel stepwise operation of thetwo stages below exposure and measurement positions. This known exampledoes not describe the structures of the two stages, and their detailsare unknown. Similarly to the method in FIG. 2B, it seems difficult toattain a stage performance as high as that of a single stage by theeffects of the mutual reaction forces of the two stages.

[0033] (B) Two Completely Independent Stages

[0034]FIG. 2C shows the arrangement of improved method 2 in aconventional semiconductor exposure apparatus. Reference numeral 40denotes an exposure wafer; 41, an exposure chuck; 42, an exposure fineadjustment stage; 43, an exposure coarse adjustment stage; 44, anexposure wafer stage surface plate; 50, a measurement wafer; 51, ameasurement chuck; 52, a measurement fine adjustment stage; 53, ameasurement coarse adjustment stage; and 54, a measurement wafer stagesurface plate.

[0035] The semiconductor exposure apparatus using this method has twocompletely independent stages. After alignment and focus measurements onthe measurement stage side, a wafer is loaded to the exposure stage sidetogether with a chuck to perform exposure on the exposure stage side. Asin improved method 1, reference marks (not shown) are formed on theedges of the chuck. The measurement and exposure stages measure thereference marks to accurately reflect alignment and focus measurementresults on the measurement stage in exposure on the exposure stage. Withthis operation, accurate alignment and focus can be implemented.

[0036] Method 2 has advantages and disadvantages as follows.

[0037] (Advantages)

[0038] Method 2 basically has advantages similar to those of method 1.In this method, two stages including stage surface plates are completelyindependent, and they never exert reaction forces on each other. Forthis reason, even if the speed of each stage increases, the precision ofscan synchronization between a reticle and a wafer can be kept high.Since method 2 basically adopts a wafer chuck transport method, and itis relatively easy to implement the chuck unloading function.

[0039] (Disadvantages)

[0040] Since method 2 requires two sets of completely independentstages, the size of the apparatus increases. The lattices of the twosets of stages need to accurately coincide with each other. The two setsare slightly separated from each other, and it is more difficult thanmethod 1 to cause the lattices to coincide with each other due toeffects of the temperature, air pressure, gas molecule composition,humidity, and the like. Also, the method needs chuck transport. Sincethe two sets are separated from each other, it is necessary to hold awafer so as to prevent the position of the wafer on a chuck fromshifting from the chuck during the chuck transport.

SUMMARY OF THE INVENTION

[0041] The present invention has as its object to propose a method ofsolving the above-mentioned problems of conventional semiconductorexposure apparatuses and solving the above-mentioned problems ofimproved methods 1 and 2. More specifically, objects to be achieved bythe present invention are as follows:

[0042] 1. an increase in throughput;

[0043] 2. facilitation of increasing the measurement precision of afocus detection system;

[0044] 3. relaxation of constraints on the design of a projectionsystem;

[0045] 4. facilitation of cleaning below the projection system;

[0046] 5. facilitation of chuck cleaning;

[0047] 6. a reduction in size of the apparatus; and

[0048] 7. facilitation of supporting a load-lock.

[0049] The present invention eventually has as its object to implement acompact common platform which can be applied to various semiconductorexposure apparatuses whose exposure spaces are an outer air space,nitrogen-purged space, vacuum space, or the like, can relax constraintson the design of the projection system and focus detection system, andcan increase the speed and precision.

[0050] To solve the above-mentioned problems and achieve the objects,according to the present invention, there is proposed a method ofarranging two independent fine adjustment stages on one coarseadjustment stage and simultaneously performing all of focus measurementand part of alignment measurement in parallel with exposure operation.

[0051] The present invention adopts a chuck transport method to easilyimplement the above-mentioned functions. The present invention proposesalignment of patterns on a wafer with a chuck before mounting the chuckon each fine adjustment stage.

[0052] According to the present invention, a more compact commonplatform which can be applied to various semiconductor exposureapparatuses, can relax constraints on the design of exposure andmeasurement units, and can increase the speed and precision can beimplemented.

[0053] Other objects and advantages besides those discussed above shallbe apparent to those skilled in the art from the description of apreferred embodiment of the invention which follows. In the description,reference is made to accompanying drawings, which form apart thereof,and which illustrate an example of the invention. Such example, however,is not exhaustive of the various embodiments of the invention, andtherefore reference is made to the claims which follow the descriptionfor determining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0054]FIG. 1 is a view showing a schematic arrangement of the presentinvention;

[0055]FIG. 2A is a view showing a typical arrangement of a conventionalsemiconductor exposure apparatus, FIG. 2B is a view showing thearrangement of a conventional improved method 1, and FIG. 2C is a viewshowing the arrangement of a conventional improved method 2;

[0056]FIG. 3 is a plain view showing the schematic arrangement of asemiconductor exposure apparatus according to an. embodiment of thepresent invention;

[0057]FIGS. 4A and 4B are plain and front views, respectively, of acoarse adjustment stage;

[0058]FIGS. 5A and 5B are plain and front views, respectively, of aprealignment unit;

[0059]FIGS. 6A to 6D are a plain view, a front view in wafer loading, afront view upon completion of coarse alignment, and a front view inwafer unloading, respectively, of the coarse alignment unit;

[0060]FIGS. 7A to 7C are plain, front, and side views, respectively,showing the structure of a chuck pipe line;

[0061]FIG. 8A is an enlarged view of the upper surface of a chuck, andFIG. 8B is a sectional view including a chuck support unit on a fineadjustment stage;

[0062]FIG. 9A is a view of a unit layout at a chuck loading position,and FIGS. 9B and 9C show how the chuck moves;

[0063]FIG. 10A is a view for explaining units at the chuck loadingposition, and FIGS. 10B and 10C show how the chuck moves;

[0064]FIG. 11 is a view for explaining the transport operation of awafer and chuck;

[0065]FIG. 12 is a view for explaining the outline of coarse alignment;

[0066]FIG. 13 is a view for explaining a chuck reference mark;

[0067]FIG. 14 is a view for explaining the outline of exposure andfocus/alignment operations;

[0068]FIG. 15 is a view for explaining the outline of chuck referencemark measurement operation;

[0069]FIG. 16A is a view for explaining an exposure focus measurementregion, and FIG. 16B is a view for explaining a measurement focusmeasurement region;

[0070] FIGS. 17 to 19 are views for explaining the outline of operationof a wafer stage unit;

[0071]FIG. 20 is a flow chart showing the operation flow of the waferstage unit; and

[0072]FIG. 21 is a view for explaining chuck unloading.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] Embodiments of the present invention will be described below indetail with reference to the accompanying drawings.

[0074] [Outline of Present Invention (FIG. 1)]

[0075]FIG. 1 shows the arrangement of an exposure apparatus according tothe present invention.

[0076] In FIG. 1, reference numeral 60 denotes an exposure wafer; 61, anexposure chuck; 62, an exposure fine adjustment stage; 70, a measurementwafer; 71, a measurement chuck (wafer chuck); 72, a measurement fineadjustment stage; 73, a coarse adjustment stage which bears the exposurefine adjustment stage 62 and measurement fine adjustment stage 72 andcan move horizontally; and 110, a coarse alignment unit arranged outsidethe coarse adjustment stage 73.

[0077] In the semiconductor exposure apparatus according to the presentinvention, the two fine adjustment stages 62 and 72 are mounted on theone coarse adjustment stage 73. The semiconductor exposure apparatus isarranged to simultaneously perform exposure and focus measurements atexposure and measurement positions by operation of the one coarseadjustment stage. When an alignment shot of the measurement wafer 70comes to near the measurement point during exposure of the exposurewafer 60, the exposure is temporarily interrupted to perform alignmentmeasurement.

[0078] A wafer having undergone alignment and focus measurements at themeasurement position on the measurement fine adjustment stage 72 issequentially transferred to the exposure position on the exposure fineadjustment stage 62 together with the measurement chuck 71, as indicatedby an arrow. Exposure operation of this wafer is performed in parallelwith measurement operation of the next wafer. This makes it possible tosimultaneously perform exposure and measurement by operation of the onecoarse adjustment stage and implement a compact high-speed exposureapparatus.

[0079] To increase the precision of focus measurement and the speed ofalignment measurement, patterns on respective wafers at the exposure andmeasurement positions preferably always have a predetermined positionalrelationship. For this reason, each pattern on the corresponding waferis aligned with respect to a chuck in the coarse alignment unit 110before loading onto the fine adjustment stages.

[0080] The conventional arrangement described in “(A) Place Two CoarseAdjustment Stages on Same Surface Plate” drives two large coarseadjustment stages. In contrast to this, the semiconductor exposureapparatus according to the present invention uses two movable units ofrespective small fine adjustment stages while the units are almostfixed, thus preventing stage interference. In other words, thesemiconductor exposure apparatus adopts a method of aligning in advancethe patterns on the wafers on the two fine adjustment stages with eachother to implement parallel exposure and measurement operations on thefine adjustment stages whose driving strokes are short.

[0081] The present invention incorporates various structuralimplementations, in addition to the above-mentioned ones. Theseimplementations will be described specifically in the followingembodiment.

[0082] [Description of Detailed Embodiment]

[0083] A semiconductor exposure apparatus according to an embodiment ofthe present invention is a scan-type one which uses an F₂ excimer laseras a light source. Since F₂ excimer laser beams are absorbed by oxygenin the air and attenuate, a space through which exposure light passesneeds to be purged with nitrogen. The semiconductor exposure apparatusof this embodiment is arranged to purge with nitrogen a space throughwhich all exposure light beams pass, including the periphery of a stage.The present invention, however, is not limited to a semiconductorexposure apparatus which uses an F₂ excimer laser as a light source andcan also be applied to EUV and EB exposure apparatuses.

[0084] [Outline of Semiconductor Exposure Apparatus (FIG. 3)]

[0085]FIG. 3 is a plain view showing the outline of the semiconductorexposure apparatus according to the embodiment of the present invention.

[0086] The semiconductor exposure apparatus of this embodiment comprisescomponents along the transport path of a wafer. In FIG. 3, referencenumeral 101 denotes a loading position of the wafer; 102, a wafer handwhich transports the wafer; 103, a loading load-lock chamber; 104, aprealignment unit; 105, a loading hand; 110, the coarse alignment unit;111, a coarse alignment scope of the coarse alignment unit 110; 112, acoarse focus sensor unit of the coarse alignment unit 110; 113, a coarsechuck stage of the coarse alignment unit 110; 120, a loading plate; 121,a chuck loading position on the loading plate 120; 122, a chuckunloading position on the loading plate 120; 123, a chuck hand whichtransports a chuck; 130, an unloading load-lock chamber; 131, anunloading hand capable of transporting the wafer or chuck; 132, anunloading Z unit which vertically drives the wafer or chuck; 140, anopen cassette; 190, outer air gate valves of the loading and unloadingload-lock chambers; 191, purge gate valves of the loading and unloadingload-lock chambers; 192, support columns of a structure (not shown)which holds a projection system 4 and an alignment scope 5; 193, loadingplate position sensors attached to the coarse adjustment stage 73 tomeasure the position of the loading plate 120; 194, a nitrogen purgespace; and 195, nitrogen purge space partition walls.

[0087] Reference numeral 4 denotes the projection system; 5, thealignment scope; 62, the exposure fine adjustment stage; 72, themeasurement fine adjustment stage; and 73, the coarse adjustment stage,as described with reference to FIGS. 1 and 2A.

[0088] (Outline of Operation)

[0089] In the semiconductor exposure apparatus of this embodiment, awafer is first loaded to the loading position 101. Atemperature-adjusting unit (not shown) is provided below the loadingposition 101 to adjust the temperature of the loaded wafer so as to fallwithin a predetermined range. When the temperature of the wafer fallswithin the predetermined range, the wafer hand 102 moves the wafer tothe prealignment unit 104 in the loading load-lock chamber 103. Theprealignment unit 104 measures the outer shape of the wafer and alignsthe wafer such that a notch formed in the wafer faces in a predeterminedrotational direction. The prealignment operation and purge of theloading load-lock chamber 103 with nitrogen are simultaneouslyperformed, thereby preventing any loss in time.

[0090] When the prealignment by the prealignment unit 104 is completed,the loading hand 105 moves the wafer from the prealignment unit 104 ontoa chuck on standby in the coarse alignment unit 110. The coarsealignment unit 110 roughly measures the position of a pattern of thewafer on the chuck and the height of the entire wafer and performsalignment such that chuck reference marks on the edges of the chuck anda predetermined pattern of the wafer have a predetermined relativepositional relationship. After that, the wafer is moved to the chuckloading position 121 on the loading plate 120, while being chucked bythe chuck hand 123. Movement of the loading plate 120 to the side of thecoarse adjustment stage 73 causes the chuck at the chuck loadingposition 121 to move onto the measurement fine adjustment stage 72 onstandby. At this position, the measurement fine adjustment stage 72moves upward and receives the chuck from the loading plate 120.

[0091] Then, the loading plate 120 retreats to the original positionshown in FIG. 3. The wafer on the measurement fine adjustment stage 72undergoes focus and alignment measurements (to be described later) andmoves onto the exposure fine adjustment stage 62 through the loadingplate 120 to perform exposure. Upon completion of the exposure, thechuck moves to the chuck unloading position 122 through the loadingplate 120.

[0092] The chuck is returned to the coarse alignment unit 110 by thechuck hand 123, and only the wafer is pulled out by the unloading hand131 in the unloading load-lock chamber 130. After the unloadingload-lock chamber 130 is purged with dry air, the wafer hand 102 returnsthe wafer to the loading position 101 and issues an unloading command toan external processing apparatus.

[0093] [Outline of Arrangement and Operation of Wafer Stage (FIGS. 4Aand 4B)]

[0094] The arrangement and operation of a wafer stage will be describedin detail.

[0095]FIGS. 4A and 4B are plain and front views, respectively, of thecoarse adjustment stage according to the embodiment of the presentinvention.

[0096] In FIGS. 4A and 4B, reference numeral 73 denotes the coarseadjustment stage; 61, the exposure chuck; 62, the exposure fineadjustment stage; 71, the measurement chuck; 72, the measurement fineadjustment stage; 201, an upper X counter mass; 202, a lower X countermass; 203, a left Y counter mass; 204, a right Y counter mass; 205, an Xdriving beam; 206, a Y driving beam; 207, X linear motor magnets; 208, Ylinear motor magnets; 210, laser interferometer exposure bar mirrors;211, laser interferometer measurement bar mirrors; 221, an exposurelaser interferometer beam X; 222, an exposure laser interferometer beamY; 223, a measurement laser interferometer beam X; 224, a measurementlaser interferometer beam Y; 230, a wafer stage surface plate; 231,wafer stage dampers; and 232, a wafer stage base plate.

[0097] (Outline of Operation)

[0098] In the semiconductor exposure apparatus of this embodiment, thewafer stage surface plate 230 is levitated by a jet of nitrogen withrespect to the wafer stage surface plate 230. The semiconductor exposureapparatus is capable of moving the coarse adjustment stage 73 in the Ydirection through the Y driving beam 206 by driving the Y linear motormagnets 208 with Y linear motor coils (not shown) and in the X directionthrough the X driving beam 205 by driving the X linear motor magnets 207with X linear motor coils (not shown).

[0099] The two fine adjustment stages, i.e., the exposure fineadjustment stage 62 and measurement fine adjustment stage 72 are mountedon the coarse adjustment stage 73. Use of laser interferometers allows Xand Y position measurements and fine driving of each fine adjustmentstage. A fine adjustment stage movable unit (not shown) in each fineadjustment stage can perform fine driving in the height (Z-axis) andtilt directions by an internal linear motor. The coarse adjustment stage73 has four counter masses, i.e., the upper X counter mass 201, lower Xcounter mass 202, left Y counter mass 203, and right Y counter mass 204mounted in a linear motor unit (not shown) to cancel any reaction forcegenerated upon driving. Driving these counter masses in a directionopposite to that of the coarse adjustment stage 73 being driven cancelsany reaction force generated by the coarse adjustment stage 73.

[0100] The coarse adjustment stage 73 is arranged on the wafer stagesurface plate 230, which is placed on the floor through the wafer stagedampers 232 for cutting off floor vibrations.

[0101] The above-mentioned stages have the following features.

[0102] (1) Driving Stroke of Each Fine Adjustment Stage

[0103] The driving stroke of the measurement fine adjustment stage 72 isset to be larger than that of the exposure fine adjustment stage 62.This is because the measurement fine adjustment stage 72 receives awafer chuck from outside the stage and needs driving to correct arelatively large error generated upon loading. The exposure fineadjustment stage 62 must maintain synchronization between a reticle andwafer at high precision in exposure, and has a short driving stroke toachieve a quick response.

[0104] (2) Mechanical Resonance Frequency

[0105] The mechanical resonance frequencies of the measurement fineadjustment stage 72 and exposure fine adjustment stage 62 are set todiffer from each other. This is to prevent any mutual interference inalignment of each fine adjustment stage.

[0106] (3) Dynamic Control of Control Parameters

[0107] In exposure operation, the control gain (parameter) of theexposure fine adjustment stage 62 is set to be high while that of themeasurement fine adjustment stage 72 is set to be low. In alignmentmeasurement to be performed during the exposure operation, the controlgain of the exposure fine adjustment stage 62 is set to be low whilethat of the measurement fine adjustment stage 72 is set to be high. Thisis because the exposure fine adjustment stage 62 requires high-precisionsynchronous control of the wafer and reticle in the exposure operationwhile the measurement fine adjustment stage 72 requires the accurateposition information of the wafer in the alignment measurement.

[0108] In the above-mentioned setting, the control gain of one fineadjustment stage is set to be high while that of the other is set to below. This is intended to prevent unnecessary vibrations from beingtransmitted from the measurement fine adjustment stage 72 to theexposure fine adjustment stage 62 in exposure or from the exposure fineadjustment stage 62 to the measurement fine adjustment stage 72 inmeasurement.

[0109] (4) Calibration of Bar Mirror for Each Fine Adjustment Stage

[0110] Each of the exposure fine adjustment stage 62 and measurementfine adjustment stage 72 is arranged to control its movable portion atthe upper portion to be locked with respect to its fixed portion at thelower portion. In this locked state, the coarse adjustment stage 73 isdriven in the X and Y directions, and laser interferometers measure theposition of each fine adjustment stage. This makes it possible tomeasure the relative error at each position in the X direction betweenthe X-measurement bar mirrors of the fine adjustment stages and therelative error at each position in the Y direction between theY-measurement bar mirrors of the fine adjustment stages. The relativeerrors between the bar mirrors are used to cause the stage coordinatesof the measurement unit and those of the exposure unit to preciselycoincide with each other.

[0111] (5) Constraints on Chuck Mounting

[0112] The coarse adjustment stage 73 is driven only when both the fineadjustment stages bear or do not bear respective chucks. This is becausethe weight balance of the coarse adjustment stage 73 needs to be keptconstant to drive the coarse adjustment stage 73 at high speed and highprecision.

[0113] (6) Loading Plate Tracking Function

[0114] The loading plate 120 is fixed on the wafer stage base plate 232,and the coarse adjustment stage 73 is placed on the wafer stage surfaceplate 230 on the wafer stage dampers. For this reason, the loading plate120 and each fine adjustment stage needs to have a predeterminedpositional relationship in transferring a chuck between them. Toimplement this, the loading plate position sensors 193 are arranged onthe coarse adjustment stage 73. In chuck transfer, each fine adjustmentstage is finely driven such that the loading plate 120 and the movableunit at the upper portion of the fine adjustment stage have apredetermined positional relationship.

[0115] [Outline of Arrangement and Operation of Prealignment (FIGS. 5Aand 5B)]

[0116]FIGS. 5A and 5B are plain and front views, respectively, of theprealignment unit of the semiconductor exposure apparatus according tothe embodiment of the present invention.

[0117] As shown in FIGS. 5A and 5B, reference numeral 103 denotes theloading load-lock chamber; 190, the outer air gate valves; 191, thepurge gate valves; 300, a wafer during prealignment; 301, a prealignmentlight-projecting unit; 302, prealignment sensors; 303, a sheet glass (onthe light-projecting unit side); 304, a sheet glass (on the sensorside); 305, a sensor support unit; 306, a purge seal unit; 307, arotation mechanism unit; 308, a Z driving unit; and 309, a wafer supportunit.

[0118] (Outline of Operation)

[0119] After the loading load-lock chamber 103 is purged with dry air,the outer air gate valves 190 are opened, and the wafer 300 is loaded tothe wafer support unit 309 by the wafer hand 102. At this time, theprealignment light-projecting unit 301 and prealignment sensors 302measure the circumferential edge position of the wafer 300 being loaded.The wafer 300 is aligned by stretching and contracting operation androtation operation of the wafer hand 102 such that the center of thewafer 300 almost coincides with that of the wafer support unit 309. Thewafer 300 is placed on the wafer support unit 309.

[0120] The rotation mechanism unit 307 on the outer air side rotates thewafer 300 through the purge seal unit 306, and the prealignment sensors302 measure the circumferential edge position of the wafer during therotation. This measurement enables more precise measurement of the waferedge position and the notch (or orientation flat) position. Hence, therotation mechanism unit 307 rotates the wafer such that the notch facesin a predetermined direction.

[0121] In the prealignment unit 104, the volume of the loading load-lockchamber 103 needs to be minimized to minimize the nitrogen purge time.To implement this, the prealignment light-projecting unit 301 andprealignment sensors 302 are arranged outside the loading load-lockchamber 103 to receive detection light into the loading load-lockchamber 103 through the sheet glass 303 (on the light-projecting unitside) and sheet glass 304 (on the sensor side).

[0122] Outer shape errors in the X and Y directions after the notch isrotated in a predetermined direction will be described later in [Outlineof Coarse Alignment].

[0123] [Outline of Arrangement and Operation of Coarse Alignment Unit(FIGS. 6A to 6D)]

[0124] The coarse alignment unit performs three major operations asfollows.

[0125] (1) The coarse alignment unit performs alignment such that areference mark on the chuck and a prealignment mark on the wafer have apredetermined relative positional relationship. The coarse alignmentunit stores shifts in the X, Y, and θ directions from the targetrelative position in this alignment.

[0126] (2) The coarse alignment unit aligns the θ direction of thereference mark on the chuck with the reference position of the coarsealignment unit. The coarse alignment unit stores shifts in the X and Ydirections from the target position.

[0127] (3) The coarse alignment unit measures the height of the uppersurface of the reference mark on the chuck and that of the upper surfaceof the wafer and stores the measurement results.

[0128] The above-mentioned functions are very important for thesemiconductor exposure apparatus according to the present invention.This is because measurements to be described later, i.e., simultaneousmeasurement of reference marks on the exposure and measurement chucks,focus measurement to be performed in parallel with exposure operation onthe exposure side, and alignment measurement on the measurement side tobe performed while the exposure operation on the exposure side istemporarily interrupted are based on the premise that patterns on thewafers on the exposure and measurement sides have a predeterminedpositional relationship at relatively high precision. The coarsealignment unit described herein performs measurements required toimplement this.

[0129] The arrangement of the coarse alignment unit will be describedbelow.

[0130]FIGS. 6A to 6D are a plain view, a front view in wafer loading, afront view upon completion of coarse alignment, and a front view inwafer unloading, respectively, of the coarse alignment unit 110 of thesemiconductor exposure apparatus according to the embodiment of thepresent invention.

[0131] As shown in FIGS. 6A to 6D, reference numeral 110 denotes theentire coarse alignment unit; 111, the coarse alignment scope; 112, thecoarse focus sensor unit; 113, the coarse chuck stage which can move inthe X direction; 401, an objective lens for measuring a chuck referencemark of the coarse alignment scope 111; 402, an objective lens fordetecting a wafer prealignment mark of the coarse alignment scope 111;403, (five) fiber sensors of the coarse focus sensor unit 112 to measurethe height of the upper surface of a chuck reference plate (to bedescribed later) and the upper surface of a wafer; 405, a chuck duringcoarse alignment; 406, a wafer during coarse alignment; 407, a chucksupport unit which holds the chuck 405 from the below and can performfine vertical and rotation driving; and 408, three wafer support pinswhich can finely drive in the X, Y, and θ directions and can operate inthe Z direction.

[0132] The coarse alignment unit 110, loading hand 105, chuck hand 123,and loading plate 120 are fixed on the wafer stage base plate 232 so asto prevent vibrations generated upon coarse alignment operation (to bedescribed later) and the like from being directly transmitted to, e.g.,the coarse adjustment stage 73 on the wafer stage surface plate 230.

[0133] (Outline of Operation)

[0134] In FIGS. 6A to 6D, the five fiber sensors 403 are arranged in thecoarse focus sensor unit 112 almost equidistantly. The two outermostfiber sensors (top and bottom ones in FIG. 6A) are used to measure theheight of the upper surface of the chuck reference plate (to bedescribed later) on the chuck 405 while the three inner fiber sensorsare used to measure the height of the upper surface of the wafer 406 onthe chuck 405. When the wafer 406 passes below the coarse focus sensorunit 112, the heights of the upper surfaces of the chuck reference plateand wafer are measured. Resultant measurement values are used to performcorrection driving in the Z and tilt directions after the chuck 405 ismounted on the measurement fine adjustment stage 72 on the coarseadjustment stage 73 and align the upper surface of the wafer within arange which allows focus measurement in final focus measurement on thecoarse adjustment stage.

[0135] The objective lens (for chuck reference marks) 401 of the coarsealignment scope 111 in FIGS. 6A to 6D is fixed to the coarse alignmentscope 111 and is used to measure two chuck reference marks (to bedescribed later) at the upper left and right positions on the chuckreference plate on the chuck.

[0136] The objective lens (for wafer marks) 402 of the coarse alignmentscope 111 can drive in the Y direction, as indicated by an arrow. Theobjective lens 402 moves to a position in the Y direction where aprealignment mark (not shown) on the wafer 406 having been specified bythe operator of the apparatus can be observed. The objective lens 402 isused to measure the position of the prealignment mark. Prealignmentmarks are generally located at two points on a wafer. The wafer 406temporarily stops four times below the coarse alignment scope 111 tomeasure the positions of the prealignment marks (twice) and chuckreference marks (twice).

[0137] The coarse chuck stage 113 has the three wafer support pins 408,which can finely drive in the X, Y, and θ directions and can also drivevertically, as indicated by inner arrows. Assume that measurementresults of the chuck reference marks and prealignment marks show thatthe prealignment marks on the wafer are not located at predeterminedpositions relative to the reference marks on the chuck and are separatedfrom the reference marks by distances of more than a tolerance. In thiscase, the three wafer support pins 408 lift the wafer 406 from the chuck405, perform for the wafer 406 fine correction driving in the X, Y, andθ directions so as to attain a predetermined positional relationship,and return the wafer 406 onto the chuck 405. With this operation, theprealignment marks on the wafer have a predetermined relative positionalrelationship with the chuck reference marks on the chuck.

[0138] An error in the θ direction of each chuck reference mark isobtained from measurement results of the two chuck reference marks. Suchan error is eliminated by finely rotating the coarse chuck stage 113.

[0139] After the above-mentioned operation, similar operation isrepeated such that the prealignment marks on the wafer are located atpredetermined positions relative to the chuck reference marks on thechuck, and an error in the θ direction of each chuck reference mark iseliminated.

[0140] Residual errors after the above-mentioned operation, i.e., thefollowing two errors (1) and (2) will be described later in [Outline ofCoarse Alignment]:

[0141] (1) residual error amounts in the X, Y, and θ directions of theprealignment marks with respect to the chuck reference marks; and

[0142] (2) residual error amounts in the X, Y, and θ directions of thechuck reference marks with respect to the coarse alignment unit.

[0143]FIG. 6B shows wafer loading. The three wafer support pins 408extend upward from the coarse chuck stage 113 through the chuck 405. Thewafer is placed on the three wafer support pins 408 by the loading hand105. The three wafer support pins 408 retracts into the coarse chuckstage 113 and passes the wafer 406 to the chuck 405. Then, the coarsechuck stage 113 starts moving to the left. When the wafer 406 comes tobelow the coarse focus sensor unit 112, the fiber sensors 403 startmeasuring the heights of the upper surfaces of the chuck reference plateand wafer.

[0144] During the measurement, the chuck reference marks on the chuckreference plate and prealignment marks on the wafer 406 come to belowthe coarse alignment scope 111. Then, the coarse alignment scope 111captures the image information of their patterns and measures thepositions of the chuck reference marks and prealignment marks on thewafer.

[0145] At this time, the height of the chuck reference plate and thoseof the prealignment marks on the wafer are already obtained by the fibersensors 403. The detection surface is always kept at the measurementimage plane position of the coarse alignment scope 111 by driving thechuck 405 in the Z direction with the coarse chuck stage 113.

[0146] Correction driving to follow is as described above. The chuckwill be described later in detail. A chuck used in the semiconductorexposure apparatus of this embodiment needs to be vacuum-chucked andfixed to the coarse chuck stage 113, measurement fine adjustment stage72, exposure fine adjustment stage 62, chuck hand 123, or loading plate120. The lower surface of the chuck has a planar structure. For thisreason, while the chuck moves among a plurality of positions, it mayshift from a predetermined position in each unit of the apparatus due toa long-term accumulation of transport errors.

[0147] To prevent this shift, the semiconductor exposure apparatus ofthis embodiment detects positional shifts in the X, Y, and θ directionsof the chuck using measurement results of the two stage reference markpositions. The semiconductor exposure apparatus eliminates a shift inthe X direction by shifting the X position of the coarse chuck stage 113in moving the chuck to the chuck hand 123, a shift in the Y direction byshifting the Y position of the chuck hand 123 in moving the chuck to thechuck hand 123, and a shift in the θ direction by rotating a chucksupport unit 412.

[0148] The overall description will be given in [Outline of CoarseAlignment].

[0149]FIG. 6C shows how the chuck is moved from the coarse alignmentunit 110 to the chuck hand 123 after the operation in the coarsealignment unit 110. FIG. 6D shows how the exposed wafer is unloaded.

[0150] As shown in FIGS. 6C and 6D, the coarse chuck stage 113 lifts thewafer 406 by the three wafer support pins 408 such that the unloadinghand 131 can pick up the wafer 406 on the chuck 405, similarly to waferloading. Though not shown in FIGS. 6C and 6D, in unloading the chuck405, the unloading hand 131 is arranged to insert its hand unit into thechuck support unit 412 below the chuck 405 and unload the chuck 405 fromthe coarse chuck stage 113.

[0151] [Outline of Structure of Chuck Pipe Line (FIGS. 7A to 7C and 8Aand 8B)]

[0152] The structure of a chuck pipe line used in the semiconductorexposure apparatus of this embodiment will be described below.

[0153] The semiconductor exposure apparatus of this embodiment adopts amethod of transporting a wafer together with a chuck. To maintain theposition of the wafer during chuck transport, a unique pipe mechanism isemployed inside the chuck.

[0154]FIGS. 7A to 7C are plain, front, and side views, respectively,showing the structure of the chuck pipe line. FIGS. 8A and 8B are anenlarged view of the upper surface of a chuck and a sectional viewincluding a chuck support unit on a fine adjustment stage.

[0155] As shown in FIGS. 7A to 7C, reference numeral 500 denotes achuck; 501, holes through which the three wafer support pins 408 of thecoarse chuck stage 113 pass in the coarse alignment unit 110; 502, waferVac. portions to which wafer Vac. pipes from the chuck hand 123 areconnected; 503, wafer Vac. valves at the inlets of the wafer Vac.portions 502; 504, wafer Vac. portions to which wafer Vac. pipes fromthe loading plate 120 are connected; 505, wafer Vac. valves at theinlets of the wafer Vac. portions 504; 506, a wafer Vac. portion towhich a wafer Vac. pipe from the exposure fine adjustment stage 62 ormeasurement fine adjustment stage 72 is connected; 507, a wafer Vac.valve at the inlet of the wafer Vac. portion 506; and 508, a waferchucked and held on the chuck 500 by a Vac. (negative pressure).

[0156] In FIG. 8A, chuck reference plates 600 are arranged at the fourcorners of the chuck. Their upper surfaces are used as references ofheight at the exposure and measurement positions. Chuck reference marks(to be described later) are formed in the chuck reference plates 600.

[0157] In FIG. 8B, reference numeral 510 denotes chuck pins arrangedwithin a region immediately below the wafer 508 and on the upper surfaceof the chuck; 511, a fine adjustment top plate attached to the uppersurface of the fine adjustment stage movable unit at the upper portionof each of the two fine adjustment stages; 512, top plate pins arrangedwithin a region immediately below the chuck 500 and on the upper surfaceof the fine adjustment top plate 511; 520, a fine adjustment wafer Vac.for chucking the wafer on the chuck by a Vac.; and 521, a fineadjustment chuck Vac. for fixing the chuck 500 on the fine adjustmenttop plate 511.

[0158] (Outline of Operation)

[0159] The chuck needs to move on the coarse chuck stage 113, chuck hand123, loading plate 120, measurement fine adjustment stage 72, andexposure fine adjustment stage 62 while holding the wafer. For thisreason, a wafer chucking Vac. can be supplied from the above-mentionedunits. When the chuck is to be moved between two of the units, it mustreceive Vac. simultaneously from the two units. The chuck of thisembodiment has a plurality of Vac. inlets and corresponding Vac. valvesinside the Vac. inlets to smoothly switch between Vac. supply lines inthis case. These valves allow switching between the Vac. supply lineswithout a special switching mechanism.

[0160] The fine adjustment top plate 511 which fixes the chuck bychucking with a Vac. has the top plate pins 512 on its upper surface,similarly to the chuck. This is intended to minimize the effect of anydust or the like attached to the lower surface of the chuck.

[0161] [Outline of Arrangement and Operation of Chuck SwitchingMechanism (FIGS. 9A to 9C and 10A to 10C)]

[0162]FIGS. 9A to 9C and 10A to 10C show an example of a chuck transportmethod according to the embodiment of the present invention. FIGS. 9A to9C and 10A to 10C illustrate how the chuck 500 is mounted from the chuckhand 123 through the loading plate 120 onto the fine adjustment topplate 511 on each fine adjustment stage.

[0163]FIG. 9A is a plain view showing the chuck hand 123 and loadingplate 120 at the chuck loading position 121; and FIGS. 9B and 9C showhow the chuck moves from the chuck hand 123 to the loading plate 120.FIG. 10A is a plain view showing the loading plate 120 and fineadjustment top plate 511 at the chuck loading position 121; and FIGS.10B and 10C show how the chuck moves from the loading plate 120 to thefine adjustment top plate 511.

[0164] Reference numeral 530 denotes chuck support units which receivethe chuck 500 from the chuck hand 123 on the loading plate 120 and holdit; 540, chuck Vac. portions which supply Vac. for chucking and holdingthe chuck 500 on the chuck support units 530 on the loading plate 120;and 541, chuck Vac. portions which supply Vac. for chucking and holdingthe chuck 500 on the chuck hand 123.

[0165] (Outline of Operation)

[0166] Operation of moving the chuck from the chuck hand 123 through theloading plate 120 onto the fine adjustment top plate 511 will bedescribed with reference to FIGS. 9B, 9C, 10B and 10C.

[0167] (1) On Chuck Hand

[0168] A state wherein the chuck 500 is on the chuck hand 123 is shownin FIG. 9B.

[0169] In this state, the chuck 500 is mounted on the chuck hand 123.The chuck 500 is chucked on the chuck hand 123 by the chuck Vac.portions 541 with a Vac. and is fixed.

[0170] The wafer 508 is chucked on the chuck 500 by a Vac. from thewafer Vac. portions 502 and is fixed.

[0171] In this state, the chuck support units 530 on the loading plate120 do not come into contact with the chuck 500.

[0172] (2) On Loading Plate

[0173] A state wherein the chuck 500 is on the loading plate 120 isshown in FIG. 9C.

[0174] This state is implemented by the following operation. In thestate shown in FIG. 9B, the wafer Vac. portions 504 and chuck Vac.portions 540 arranged on the chuck support units 530 on the loadingplate 120 are brought into a Vac. state. The chuck hand 123 is moveddownward to a predetermined position, and the chuck Vac. portions 541and the wafer Vac. portions 502 on the chuck hand 123 side are switchedfrom the Vac. state to an atmospheric state. The chuck hand 123 isfurther moved downward.

[0175] A chuck holding unit of the chuck hand 123 has a verticalfriction mechanism (not shown) to prevent an overload of a predeterminedmagnitude or more on the chuck hand 123 and chuck support units 530 inthe above-mentioned operation.

[0176] (3) Above Fine. Adjustment Stage

[0177] When the chuck 500 is fixed on the loading plate 120, the loadingplate 120 moves from outside the coarse adjustment stage 73 onto thecoarse adjustment stage 73.

[0178] In this state, the coarse adjustment stage 73 moves a movableunit at the upper portion of the measurement fine adjustment stage 72 onthe coarse adjustment stage 73 downward and moves to a position where itfits into the loading plate 120. The state at this time is shown in [3.Above Fine Adjustment Stage] In this state, the chuck 500 is held on thechuck support units 530 on the loading plate 120 by the chuck Vac.portions 540, as described in FIG. 10B. The wafer 508 is chucked andheld with a Vac. on the chuck by the wafer Vac. portions 504 on thechuck support units 530 on the loading plate 120.

[0179] (4) On Fine Adjustment Stage Top Plate

[0180] A state wherein the chuck 500 moves onto the fine adjustment topplate 511 is shown in FIG. 10C.

[0181] This state is implemented by the following operation. In thestate shown in FIG. 10B, the fine adjustment wafer Vac. 520 and fineadjustment chuck Vac. 521 on the fine adjustment top plate 511 side arebrought into a Vac. state. The fine adjustment top plate 511 is movedupward to a predetermined position, and the chuck Vac. portions 540 andthe wafer Vac. portions 504 on the loading plate 120 side are switchedfrom the Vac. state to an atmospheric state. The fine adjustment topplate 511 is further moved upward.

[0182] [Transport Operation of Wafer and Chuck (FIG. 11)]

[0183] The operations of the units have been described above. Operationof transporting a wafer and chuck by the entire apparatus, in whichthese operations are combined, will be described with reference to FIG.11. Reference numerals in FIG. 11 denote the chronological order andcorrespond to the parenthesized numbers in the following description.Narrow lines indicate wafer movement while wide lines indicate chuckmovement.

[0184] (1) The wafer is loaded to the loading position 101 by anexternal apparatus (e.g., a coater/developer).

[0185] A temperature-adjusting function (not shown) is also arranged atthis position. The wafer is made to stand by until its temperaturereaches a predetermined value.

[0186] (2) The wafer hand 102 loads the wafer from the loading position101 to the prealignment unit 104 in the loading load-lock chamber 103.

[0187] At this time, the wafer hand 102 performs rough alignment usingthe prealignment sensors 302. Concurrently with the start of nitrogenpurge, the edge position of the wafer is measured while the wafer isrotated. On the basis of the measurement result, a notch or orientationflat is made to face in a predetermined rotational direction, and erroramounts in the X and Y directions are calculated.

[0188] (3) The loading hand 105 moves the wafer from the prealignmentunit 104 onto the chuck on the coarse chuck stage 113 of the coarsealignment unit 110. At this time, as for the error amounts in the X andY directions calculated in (2), the error in the Y direction iscorrected by correcting the pick-up position of the loading hand whilethe error in the X direction is corrected by correcting the X positionof the coarse chuck stage 113 in wafer mounting. Note that the wafer istransported on the chuck in subsequent operation.

[0189] (4) The coarse alignment unit 110 measures the height of theentire wafer surface by using a chuck reference plate as a referencewhen the coarse chuck stage 113 passes below the coarse focus sensorunit 112 and coarse alignment scope 111. The coarse alignment unit 110detects the positions of chuck reference marks on the chuck referenceplate and prealignment marks in the wafer and performs correctiondriving with the three wafer support pins 408 such that the prealignmentmarks on the wafer are located at predetermined positions relative tothe chuck reference marks. An error in the θ direction of each chuckreference mark is also corrected by this correction driving.

[0190] (5) When the coarse alignment operation ends, the coarse chuckstage 113 moves to the transfer position of the chuck hand 123.

[0191] (6) The chuck hand 123 moves the chuck on the coarse chuck stage113 to the chuck loading position 121 on the loading plate 120 while thechuck holds the wafer thereon. At this time, as for the error amounts inthe X and Y directions of the chuck reference marks calculated in (4),the error in the X direction is eliminated by correcting and driving theposition of the coarse chuck stage 113 in the X direction in thetransfer operation while the error in the Y direction is eliminated bycorrecting and driving the position of the chuck hand 123 in the Ydirection in the transfer operation.

[0192] (7) The loading plate 120 moves to the coarse adjustment stage 73side (apparatus center side) and at this position, moves the chuck fromthe loading plate 120 onto the fine adjustment top plate 511 on themeasurement fine adjustment stage 72. Upon completion of the movement,the loading plate 120 externally retreats from the coarse adjustmentstage 73. After that, the measurement fine adjustment stage 72 issubjected to focus/alignment measurement operation, and a detaileddescription thereof will be given later.

[0193] (8) Upon completion of the measurement operation, the loadingplate 120 moves to the side of the coarse adjustment stage 73, whichtemporarily returns the chuck to the loading plate 120.

[0194] (9) The coarse adjustment stage 73 passes the chuck to theloading plate 120. The empty coarse adjustment stage 73 moves in adownward direction with respect to the sheet surface of FIG. 11 andreceives the chuck from the loading plate 120. With this operation, thechuck having undergone measurement moves from the measurement fineadjustment stage 72 onto the exposure fine adjustment stage 62. Afterthat, the loading plate 120 retreats externally. The chuck having movedto the exposure fine adjustment stage 62 is subjected to exposureoperation.

[0195] (10) Upon completion of the exposure operation, the loading plate120 moves again to the coarse adjustment stage 73 side, and the chuckhaving undergone exposure moves to the chuck unloading position 122 onthe loading plate 120.

[0196] (11) The chuck having moved to the loading plate 120 externallyretreats from the coarse adjustment stage 73 by external movement of theloading plate 120.

[0197] (12) The chuck hand 123 returns the chuck having retreated fromthe coarse adjustment stage 73 to the coarse chuck stage 113 of thecoarse alignment unit 110.

[0198] (13) The coarse chuck stage 113 moves to the wafer unloadingposition and at this position, causes the three wafer support pins 408to extend upward, thereby lifting the wafer from the chuck.

[0199] (14) The unloading hand 131 in the unloading load-lock chamber130 recovers the wafer into the unloading load-lock chamber. After theunloading load-lock chamber 130 recovers the wafer, the atmosphere inthe unloading load-lock chamber 130 is purged of nitrogen with dry air.Then, the wafer is moved upward by the unloading Z unit 132 at thecentral portion.

[0200] (15) The wafer hand 102 unloads the wafer from the unloading Zunit 132 and moves it to the loading position 101.

[0201] (16) In parallel with the operations in (14) and (15), the emptychuck from which the wafer has been removed by the unloading hand 131moves again to the wafer loading position of the coarse alignment unitand waits until the loading of the next wafer.

[0202] (17) The wafer having been returned to the loading position 101is recovered by an external apparatus.

[0203] The operation of the wafer and chuck has sequentially beendescribed mainly from the aspect of transport operation. The units in anactual exposure apparatus operate in parallel. An explanation with anemphasis on this parallel operation will be given after a description ofthe operation of the stage unit in, e.g., alignment measurement andexposure.

[0204] [Outline of Coarse Alignment (FIG. 12)]

[0205] In this embodiment, as described above, the two fine adjustmentstages are arranged on the one coarse adjustment stage, therebyperforming simultaneous measurement of reference marks on the exposureand measurement chucks, focus measurement on the measurement side to beperformed in parallel with exposure operation on the exposure side, andalignment measurement on the measurement side to be performed while theexposure operation on the exposure side is temporarily interrupted. Toimplement these measurements on the coarse adjustment stage, thefollowing three conditions must be satisfied on the coarse adjustmentstage.

[0206] (1) Predetermined patterns of a wafer on the exposure fineadjustment stage and those of a wafer on the measurement fine adjustmentstage have a predetermined relative positional relationship.

[0207] (2) Chuck reference marks on the exposure fine adjustment stageand those on the measurement fine adjustment stage have a predeterminedrelative positional relationship.

[0208] (3) Rough measurement of the height of the wafer on themeasurement fine adjustment stage is completed, and tilt correction(global tilt correction) of the entire wafer can be performed.

[0209] The semiconductor exposure apparatus of this embodiment performsthe following coarse alignment and coarse focus measurement to satisfythe above-mentioned conditions.

[0210] A coarse measurement system will be explained. Note that part ofits description may be repetitive.

[0211] The parenthesized numbers in FIG. 12 indicate correction drivingpositions where coarse alignment is performed and measurement positionswhere coarse focus measurement is performed in the followingdescription.

[0212] (Wafer Coarse Alignment)

[0213] Wafer coarse alignment consists of the following three steps, anda unit other than the coarse alignment unit performs part of theoperation.

[0214] (1) Alignment in Prealignment Unit

[0215] When a wafer is to be loaded to the prealignment unit 104, thecenter of the wafer is set to the almost center of the wafer supportunit 309 of the prealignment unit 104. Then, the position of a notch (ororientation flat) is detected, and the wafer is rotated such that thenotch faces in a predetermined direction.

[0216] (2) Alignment at Wafer Loading Position in Coarse Alignment Unit

[0217] Outer shape errors in the X and Y directions after the notch isrotated in a predetermined direction are eliminated at the wafer loadingposition of the coarse alignment unit. The error in the Y direction iseliminated by correcting the Y position of the loading hand 105 inloading while the error in the X direction is eliminated by correctingthe X position of the coarse chuck stage 113 in loading. On the basis ofthe outer shape measurement result, the wafer is loaded to a positionwhere the positions of prealignment marks in the wafer are located atpredetermined positions relative to chuck reference marks.

[0218] (3) Prealignment in Coarse Alignment Unit

[0219] It is difficult to cause the prealignment marks in the wafer tohave a predetermined positional relationship with the chuck referencemarks on the basis of only the outer shape measurement result. For thisreason, the coarse alignment unit measures the positions of theprealignment marks in the wafer. As needed, the three wafer support pins408 lift the wafer to align the prealignment marks with the chuckreference marks. The positions of the prealignment marks are measuredagain. This operation is repeated until a positional shift becomes equalto or smaller than a predetermined tolerance.

[0220] Note that above-mentioned operation is performed simultaneouslywith reference mark measurement and correction driving of an error inthe θ direction of a chuck shown in (5) below.

[0221] Correction driving for residual error amounts in the X, Y, and θdirections from a predetermined relative position is performed after thechuck is mounted on the measurement fine adjustment stage. Thecorrection driving is performed such that the wafer on the exposure fineadjustment stage and its patterns have a predetermined relativepositional relationship in fine alignment measurement on the measurementfine adjustment stage (to be described later).

[0222] (Chuck Coarse Alignment)

[0223] Chuck coarse alignment includes the following two steps.

[0224] (4) Measurement of Reference Mark in Empty Chuck

[0225] The empty chuck from which the wafer has been removed by theunloading hand 131 at the wafer unloading position undergoes chuckreference mark position measurement by the coarse alignment scope 111 ofthe coarse alignment unit 110 and obtains positional shift amountsbefore loading the next wafer. The positional shift amount in the θdirection is eliminated by rotating the chuck on the coarse chuck stage.The positional shifts in the X and Y directions are eliminatedsimultaneously with correction of the Y position of the loading hand andthe X position of the coarse chuck stage in the wafer loading describedabove. This reduces a correction amount after wafer loading.

[0226] (5) Reference Mark Measurement after Wafer Loading

[0227] The positions of the chuck reference marks are measuredsimultaneously with the wafer prealignment in (3) to obtain positionalshift amounts of the chuck. Out of the positional shift amounts, theerror in the θ direction is eliminated by finely rotating the coarsechuck stage 113. To eliminate the residual error amounts in the X and Ydirections, the Y position of the chuck hand 123 and the X position ofthe coarse chuck stage 113 are corrected in loading the chuck to thechuck loading position 121 on the loading plate 120. With thisoperation, the chuck reference marks are located at predeterminedpositions on the chuck loading position 121.

[0228] A residual error amount in the θ direction after fine rotation ofthe coarse chuck stage 113 will be described. The measurement fineadjustment stage 72 is rotated in an opposite direction by the residualerror amount in loading the chuck to the measurement fine adjustmentstage 72 and is returned to the original position after the chuckloading. This reduces the residual error amount in the θ direction afterloading the chuck to the measurement fine adjustment stage 72.

[0229] (Wafer Coarse Focus Measurement)

[0230] Wafer coarse focus measurement is performed as follows.

[0231] (6) As described in [Outline of Arrangement and Operation ofCoarse Alignment Unit], the coarse alignment unit 110 measures theheight of the upper surface of the wafer at each position in the X and Ydirections. The average focus plane (global focus plane) of the waferwith reference to a chuck reference plane (to be described later) iscalculated from a measurement value of the height and the chuckreference plane. After the wafer is loaded onto the measurement fineadjustment stage 72, the measurement fine adjustment stage is driven inthe height and tilt directions such that the global focus planecoincides with the measurement image plane of the alignment scope 5 of ameasurement unit and the measurement height of a focus measurement unit(focus detection system) 6. This can narrow the measurement range of thefocus measurement unit and can increase the focus measurement precision.Additionally, this can minimize a correction driving amount after themeasurement and can minimize driving errors. In alignment measurement aswell, this can minimize focus shifts generated upon wafer movement andcan increase the alignment precision.

[0232] Such a height measurement value is also used to align the uppersurface of the wafer on the measurement image plane of the alignmentscope in the wafer prealignment measurement.

[0233] (Chuck Coarse Focus Measurement)

[0234] Chuck coarse focus measurement is performed as follows.

[0235] (7) As described in [Outline of Arrangement and Operation ofCoarse Alignment Unit], the coarse alignment unit 110 measures in theheight direction the upper surfaces of the four chuck reference plates600 on the edges of the chuck. After the chuck is loaded onto themeasurement fine adjustment stage, the measurement unit of the coarseadjustment stage measures the heights of three or more chuck referenceplates, thereby obtaining the chuck reference plane. The global focusplane of the wafer is calculated and aligned with reference to theposition of the reference plane.

[0236] Note that such a height measurement value is also used to alignthe upper surfaces of the reference marks on the measurement image planeof the alignment scope in the reference mark measurement.

[0237] [Outline of Chuck Reference Mark (FIG. 13)]

[0238]FIG. 13 shows a chuck reference mark.

[0239] In FIG. 13, reference numeral 500 denotes the chuck; 600, thechuck reference plates arranged at predetermined positions at fourcorners of the chuck 500; 601, measurement areas for electrostaticcapacitance sensors which measure the heights of the chuck referenceplates; and 602, chuck reference marks located on the chuck referenceplates.

[0240] In the exposure apparatus of this embodiment, the chuck referenceplates are arranged at the four corners of the chuck 500, as shown inFIG. 13. Each chuck reference plate is made of quartz and has themeasurement area 601 for the electrostatic capacitance sensor on itssurface. The measurement area 601 is a conductive pattern and isconnected to a ground position in the exposure apparatus such that theelectrostatic capacitance sensor can perform high-precision andhigh-stability measurement. The position of the upper surface of themeasurement area is used as a reference of the height of the chuck. Theheight is measured by a plurality of electrostatic capacitance sensorsattached to the lower surface of the projection system at an exposureposition and the lower surface of the alignment scope of the measurementunit at a measurement position.

[0241] [Outline of Exposure and Focus/Alignment Operations (FIG. 14)]

[0242] As one of the characteristic features of the exposure apparatusof this embodiment, exposure and measurement operations are performed inparallel on two fine adjustment stages on one coarse adjustment stage.

[0243] Operation on the coarse adjustment stage will be described below.

[0244]FIG. 14 shows the outline of focus/alignment operations; FIG. 15,the outline of chuck reference mark measurement operation; FIG. 16A, thefocus measurement region of a chuck reference mark on the exposure side;and FIG. 16B, the focus measurement region of a chuck reference mark onthe measurement side.

[0245] In FIG. 14, reference numeral 60 denotes the exposure wafer onthe exposure chuck 61; 70, the measurement wafer on the measurementchuck 71; 610, alignment shots which need alignment measurement; 611, analignment mark for fine alignment measurement located near the alignmentshot 610; 620, an exposure path of the exposure wafer 60; and 630, ameasurement path of the measurement wafer 70. In FIG. 15, referencenumeral 650 denotes an alignment scope which can simultaneously measurea reticle and chuck reference marks; 651, an objective lens of thealignment scope 650; 652, a low-magnification measurement expander ofthe alignment scope 650; 653, a low-magnification measurement CCD cameraof the alignment scope 650; 654, a high-magnification measurement CCDcamera of the alignment scope 650; 5, the alignment scope arranged at anoff-axis position; 660, an objective lens of the alignment scope 5; 661,a low-magnification measurement expander of the alignment scope 5; 662,a low-magnification measurement CCD camera of the alignment scope 5;663, a high-magnification measurement CCD camera of the alignment scope5; 671 to 674, small electrostatic capacitance sensors arranged aroundthe image plane of the projection system 4 to measure the positions ofthe upper surfaces of the corresponding chuck reference plates at anexposure position; and 675 to 678, small electrostatic capacitancesensors arranged around the measurement position of the alignment scope5 so as to have the same positional relationship as that of theelectrostatic capacitance sensors 671 to 674 to measure the positions ofthe upper surfaces of the corresponding chuck reference plates at ameasurement position.

[0246] Note that the measurement image plane of the alignment scope 650is located at almost the center of the measurement ranges of theelectrostatic capacitance sensors 671 to 674. The measurement imageplane of the alignment scope 5 is located at almost the center of themeasurement ranges of the electrostatic capacitance sensors 675 to 678.

[0247] In FIG. 16A, reference numeral 680 denotes an exposure regionsize which indicates the size of an exposure region; and 681 to 684,measurement points of electrostatic capacitance sensors S1 to S4arranged on the lower surface of the projection system 4 at the exposureposition.

[0248] In FIG. 16B, reference numerals 685 to 688 denote measurementpoints of electrostatic capacitance sensors S5 to S8 arranged on thelower surface of the alignment scope 5 at the measurement position.Reference numerals 691 to 695 denote measurement points of focus sensorsR1 to R5 arranged on the lower surface of the alignment scope 5 at themeasurement position.

[0249]FIG. 15 shows only one focus detection system 6 and only one focusdetection system 7. In practice, five detection systems 6 and fivedetection systems 7 are provided in a direction perpendicular to thesheet surface of FIG. 15. The measurement points 691 to 695 of the focussensors R1 to R5 correspond to detection positions of these detectionsystems.

[0250] (Outline of Operation)

[0251] (1) First Reference Mark Measurement at Measurement Position

[0252] In the semiconductor exposure apparatus of this embodiment, whenthe measurement chuck 71 is mounted on the measurement fine adjustmentstage 72 on the coarse adjustment stage 73, the coarse adjustment stage73 is driven in the X and Y directions. This driving is performed suchthat the chuck reference mark 602 of the upper right chuck referenceplate out of the chuck reference plates 600 on the exposure chuck 61 andthe chuck reference mark 602 on the upper right chuck reference plateout of the chuck reference plates 600 on the measurement chuck 71simultaneously fall within the measurement areas of the alignment scope650 and alignment scope 5, respectively.

[0253] At this time, as for the heights of the reference plates at thefour corners of the measurement chuck 71, the reference plane for thereference plates are calculated from the measurement results of thereference plates at the four corners by the coarse alignment unit. Themeasurement fine adjustment stage 72 drives the measurement chuck 71 inthe height and tilt directions before the reference mark positionmeasurement such that the reference plane coincides with the measurementimage plane of the alignment scope 5.

[0254] The electrostatic capacitance sensors S5 to S8 precisely measurein advance the heights of the reference plates of the exposure chuck 61while the chuck is on the measurement fine adjustment stage 72. Hence,the exposure fine adjustment stage 62 drives the exposure chuck 61 inthe height and tilt directions on the basis of the measurement resultbefore the reference mark position measurement such that the uppersurfaces of the reference plates coincide with the measurement imageplane of the alignment scope 650.

[0255] With the above-mentioned operation, the observation plane of eachreference plane is located at the measurement image plane of thecorresponding alignment scope.

[0256] After that, at the measurement position, the electrostaticcapacitance sensors S5 to S8 arranged around the measurement image planeof the alignment scope 5 perform precise height measurement of thereference plates and perform correction driving in the height directionfor the measurement fine adjustment stage such that the upper surfacesof the reference plates accurately coincide with the measurement imageplane of the alignment scope 5. Then, the alignment scope 5 preciselymeasures the reference marks.

[0257] At the exposure position, in parallel with the above-mentionedoperation, the electrostatic capacitance sensors S1 to S4 arrangedaround the measurement image plane of the alignment scope 650 performprecise height measurement of the reference plates and performcorrection driving in the height direction for the exposure fineadjustment stage such that the upper surfaces of the reference platesaccurately coincide with the measurement image plane of the alignmentscope 650. Then, the alignment scope 650 precisely measures thereference marks.

[0258] The alignment scopes 5 and 650 perform position measurement usinginput images from the high-magnification measurement CCD cameras 663 and654 and at the same time, perform measurement using thelow-magnification measurement CCD cameras 662 and 653. If each referencemark falls outside a high-magnification measurement range, the coarseadjustment stage 73 and the exposure fine adjustment stage 62 ormeasurement fine adjustment stage 72 is driven such that the referencemark falls within the high-magnification measurement range.

[0259] (2) Second Reference Mark Measurement at Measurement Position

[0260] The coarse adjustment stage is driven such that the chuckreference mark 602 of the lower right chuck reference plate out of thechuck reference plates 600 on the exposure chuck 61 and the chuckreference mark 602 on the lower right chuck reference plate out of thechuck reference plates 600 on the measurement chuck 71 simultaneouslyfall within the measurement areas of the alignment scope 650 andalignment scope 5, respectively. Then, measurement similar to (1) isperformed.

[0261] (3) Third Reference Mark Measurement at Measurement Position

[0262] The coarse adjustment stage is driven such that the chuckreference mark 602 of the lower left chuck reference plate out of thechuck reference plates 600 on the exposure chuck 61 and the chuckreference mark 602 on the lower left chuck reference plate out of thechuck reference plates 600 on the measurement chuck 71 simultaneouslyfall within the measurement areas of the alignment scope 650 andalignment scope 5, respectively. Then, measurement similar to (1) and(2) is performed.

[0263] After the above-mentioned operation, at the measurement position,the precise X and Y positions of each chuck reference mark 602 of themeasurement chuck 71 and the reference plane for the reference mark arecalculated while at the exposure position, the precise X and Y positionsof each chuck reference mark 602 of the exposure chuck 61 and thereference plane for the reference mark are calculated.

[0264] (4) Exposure and Focus Measurement

[0265] With the above-mentioned operation, precise position measurementis completed for the chuck reference marks of the measurement chuck 71and exposure chuck 61. As indicated by the exposure path 620 of FIG. 14,operation of the coarse adjustment stage causes the exposure chuck 61 tostart exposure operation.

[0266] In the exposure operation, various correction operations areperformed using results of focus and alignment measurements obtained inadvance by the measurement unit. A detailed description will be givenafter the chuck of the measurement unit is moved to the exposure unit.

[0267] In parallel with the exposure operation of the exposure chuck 61,the measurement side performs focus measurement of a measurement shot ofthe wafer on the measurement chuck 71, which is located at the sameposition of an exposure shot on the wafer on the exposure chuck 61. Atthis time, since the height of the wafer on the measurement chuck 71 isobtained in advance from the measurement result by the coarse focussensor unit, the global focus plane of the wafer is calculated. Themeasurement fine adjustment stage 72 drives the measurement chuck 71 inthe height and tilt directions such that the global focus planecoincides with the measurement position of the focus detection system 7before the focus measurement. This allows high-precision focusmeasurement of the entire wafer.

[0268] Before the focus measurement, the measurement fine adjustmentstage 72 is also driven such that the position of a specific pattern ofthe wafer on the measurement chuck 71 and that of a specific pattern ofthe wafer on the exposure chuck 61 have a predetermined positionalrelationship.

[0269] This operation is required to always set focus measurement pointson the wafer at predetermined positions and attain high-precision focusmeasurement. This operation is also required to align the alignment mark611 within the measurement region in high-magnification measurement bythe alignment scope 5 at the time of alignment measurement duringexposure (to be described later) and perform precise positionmeasurement.

[0270] This operation is performed by calculating the target drivingposition of the measurement fine adjustment stage 72 from themeasurement results of the positions of the chuck reference marks andthe prealignment marks in the wafer obtained in advance by the coarsealignment unit 110 and the measurement results of the chuck referencemark positions described in (1) to (3).

[0271] (5) Exposure and Alignment Measurement

[0272] As described above, exposure for the wafer on the exposure chuck61 and focus measurement for the wafer on the measurement chuck 71 areperformed in parallel. When each alignment shot 610 comes to near aposition where the focus measurement is performed, scan exposureoperation is temporarily stopped. High-magnification measurement of thealignment scope 5 performs precise position measurement for thealignment mark 611 of the alignment shot 610.

[0273] The coarse adjustment stage 73 is temporarily stopped for thealignment measurement. The semiconductor exposure apparatus of thisembodiment follows the measurement path 630 shown in FIG. 14, i.e.,switchbacks in the Y direction and needs to stop temporarily.

[0274] The semiconductor exposure apparatus of this embodimenttemporarily stops in the X direction in the temporary stop operation inthe Y direction and performs precise position measurement of the waferon the measurement chuck 71. The semiconductor exposure apparatus canminimize the time necessary for alignment measurement operation.

[0275] In FIG. 14, alignment measurement is performed for a measurementshot not having undergone focus measurement. When a measurement shothaving undergone focus measurement comes to near the measurementposition during exposure operation, the same operation may be performed.

[0276] In this case, use of focus measurement data for each shot enablesnot focus alignment of only the global focus plane but more accuratefocus alignment for alignment shots, thereby allowing more precisealignment measurement.

[0277] (6) Last Reference Mark Measurement

[0278] Upon completion of exposure of the wafer on the exposure chuck 61and focus and alignment measurements of the wafer on the measurementchuck 71, the coarse adjustment stage operates to move the chuckreference marks on the exposure chuck 61 and the chuck reference markson the measurement chuck 71 below the alignment scopes 650 and 5.High-magnification measurement of each alignment scope confirms whetherthe exposure and measurement operations cause any positional shift ofeach chuck. If the measurement result detects a shift amount of apredetermined tolerance or more, each chuck is recovered to the loadingplate 120. In this state, nitrogen for cleaning is ejected from eachfine adjustment stage to perform cleaning.

[0279] When the positional shift amount approaches the predeterminedtolerance, a warning is issued. If the positional shift amount is toolarge to correct by the cleaning, the apparatus stops abnormally.

[0280] (7) Movement from Measurement Fine Adjustment Stage to ExposureFine Adjustment Stage

[0281] When all the measurements at the measurement position arecompleted, the coarse adjustment stage moves to the right rear. Theloading plate 120 moves to the coarse adjustment stage side (right side)and reaches the upper portion of the right half of the coarse adjustmentstage. The two fine adjustment stages on the coarse adjustment stage 73are moved at a normal height to the left rear and are fit into theloading plate 120.

[0282] At this position, each fine adjustment stage turns off the Vac.of the corresponding chuck and moves downward, thereby moving the chuckonto the loading plate 120. Then, the coarse adjustment stage 73 ismoved to the left front, and at this position, each fine adjustmentstage is moved upward. With this operation, unloading of a chuck holdinga wafer having undergone exposure, movement of a chuck holding a waferhaving undergone measurement from the measurement fine adjustment stage72 to the exposure fine adjustment stage 62, and loading of a chuckholding a wafer to be measured next onto the measurement fine adjustmentstage 72 are performed.

[0283] A detailed description will be given in [Outline of Operation ofWafer Stage Unit (FIGS. 17 to 20)].

[0284] (8) First Reference Mark Measurement at Exposure Position

[0285] Operation at the exposure position described in “(1) FirstReference Mark Measurement at Measure Position” is performed.

[0286] (9) Second Reference Mark Measurement at Exposure Position

[0287] Operation at the exposure position described in “(2) SecondReference Mark Measurement at Measure Position” is performed.

[0288] (10) Third Reference Mark Measurement at Exposure Position

[0289] Operation at the exposure position described in “(3) ThirdReference Mark Measurement at Measure Position” is performed.

[0290] (11) Exposure

[0291] An explanation of various correction operations in exposure isomitted from “(4) Exposure and Focus Measurement” and will be givenbelow.

[0292] The positions of the upper surface of the wafer to be exposed atthe X and Y positions and the positions of the alignment marks of thealignment shots on the wafer with reference to the chuck reference marksare obtained from the measurement results obtained in (1) to (5).

[0293] When each of the positions of the upper surface of the wafer atthe X and Y positions comes to the exposure position, the exposure fineadjustment stage 62 drives the wafer such that the position accuratelycoincides with the exposure image plane of the projection system 4.

[0294] The measurement result of the position of each alignment mark isdecomposed after the measurement into wafer position errors in the X, Y,and θ directions, a wafer magnification error, an X-Y arrayorthogonality error, and the like. These errors are corrected by thecoarse adjustment stage 73 in exposure, the position of the exposurefine adjustment stage .62, the scan rates of the reticle and wafer,magnification correction of the projection system, and the like.

[0295] [Outline of Operation of Wafer Stage Unit (FIGS. 17 to 20)]

[0296] The semiconductor exposure apparatus of this embodiment performsexposure and measurement operations in parallel on one coarse adjustmentstage. This parallel operation will be described below in detail.

[0297] FIGS. 17 to 19 show the outline of operation of a wafer stage. InFIGS. 17 to 19, reference symbols A and B denote empty chucks, and achuck on which a wafer is mounted bears the number of the wafer.

[0298] Note that a chuck holding wafer No. 1 will be referred to aschuck No. 1 hereinafter. FIG. 20 is the operation flow of FIGS. 17 to19. The circled process numbers are the same as those shown in FIGS. 17to 19.

[0299] (Outline of Operation)

[0300] The sequence from the beginning to the end of the wafer processof the semiconductor exposure apparatus according to this embodiment ismainly divided into the following six blocks in the case of N wafers.

[0301] (1) Measurement of First Wafer

[0302] (2) (Measurement of Second Wafer) & (Exposure of First Wafer)

[0303] (3) (Measurement of Third to (N−1)th Wafers) & (Exposure ofSecond to (N−2)th Wafers)

[0304] (4) (Measurement of Nth Wafer) & (Exposure of (N−1)th Wafer)

[0305] (5) Exposure of Nth Wafer

[0306] (6) End Process

[0307] These blocks will be explained below in detail.

[0308] (1) Measurement of First Wafer

[0309] No. 1: Movement of First Wafer onto Loading Plate

[0310] The semiconductor exposure apparatus of this embodimentincorporates three chucks, which stand by at the following positions intheir initial states.

[0311] At the wafer loading position on the coarse alignment unit 110

[0312] On the exposure fine adjustment stage 62

[0313] On the measurement fine adjustment stage 72

[0314] Upon completion of coarse alignment in the coarse alignment unit110, the first wafer is loaded at the chuck loading position 121 on theloading plate 120 by the chuck hand 123, as shown in FIG. 17. Note thatthe chuck hand 123 retreats and stands by at the rearmost position.

[0315] No. 2: Insertion of Loading Plate

[0316] The loading plate 120 is inserted into the coarse adjustmentstage 73. The coarse adjustment stage moves to the unloading position(left rear) while the exposure fine adjustment stage 62 and measurementfine adjustment stage 72 are kept elevated, and the fine adjustmentstages move downward. With this operation, the empty chucks A and B moveonto the loading plate 120.

[0317] No. 3: Movement of Coarse Adjustment Stage to Loading Position

[0318] After the empty chucks A and B are passed to the loading plate120, the coarse adjustment stage 73 moves from the unloading position(left rear) to the loading position (left front). At this position, theexposure fine adjustment stage 62 and measurement fine adjustment stage72 move upward. The empty chuck B is coupled to the exposure fineadjustment stage 62 while chuck No. 1 holding the first process wafer iscoupled to the measurement fine adjustment stage 72.

[0319] No. 4: Retreat of Loading Plate

[0320] The loading plate 120 externally retreats from the coarseadjustment stage 73, and movement of the empty chuck B and chuck No. 1to the coarse adjustment stage 73 completes. The empty chuck A on theloading plate 120 is unloaded by the chuck hand 123 to the coarsealignment unit 110.

[0321] No. 5: Reference Mark Measurement (on Measurement Side)

[0322] The electrostatic capacitance sensors S5 to S8 on the measurementside measure the upper surfaces of the chuck reference plates on chuckNo. 1, and at the same time, the focus detection system 7 performs focusmeasurement. The electrostatic capacitance sensors S5 to S8 and focusdetection system 7 perform calibration. The alignment scope(simultaneous measurement at low and high magnifications) on themeasurement side measures the chuck reference marks 602 in the chuckreference plates 600 on chuck No. 1.

[0323] Though not shown, the two or more chuck reference marks 602 aremeasured.

[0324] No. 6: Focus Measurement

[0325] The coarse adjustment stage 73 is driven in the same manner as inactual exposure, and the focus detection system 7 on the measurementside performs focus measurement for the entire upper surface of chuckNo. 1.

[0326] If an alignment shot comes to near a position where focusmeasurement is being performed by the alignment scope 5(high-magnification) on the measurement side, alignment measurement isalso performed, as shown in FIG. 14.

[0327] During this operation, chuck No. 2 is moved to the chuck loadingposition 121 of the loading plate 120, as shown in FIG. 17.

[0328] No. 7: Reference Mark Measurement (on Measurement Side)

[0329] After the measurement, the alignment scope 5 (high-magnification)on the measurement side measures the chuck reference marks 602 in thechuck reference plates 600 on chuck No. 1.

[0330] It is confirmed whether the measurement operation causes anypositional shift of the chuck.

[0331] (2) (Measurement of Second Wafer) & (Exposure of First Wafer)

[0332] No. 8: Insertion of Loading Plate

[0333] The loading plate 120 is inserted. Then, the coarse adjustmentstage 73 moves to the unloading position (left rear) while the exposurefine adjustment stage 62 and measurement fine adjustment stage 72 arekept elevated, and the fine adjustment stages move downward. With thisoperation, the empty chuck B and chuck No. 1 are moved onto the loadingplate 120.

[0334] No. 9: Movement of Coarse Adjustment Stage to Loading Position

[0335] After the empty chuck B and chuck No. 1 are passed to the loadingplate 120, the coarse adjustment stage 73 moves from the unloadingposition (left rear) to the loading position (left front).

[0336] At this position, the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move upward. Chuck No. 1 is coupledto the exposure fine adjustment stage 62 while chuck No. 2 holding thesecond process wafer is coupled to the measurement fine adjustment stage72.

[0337] No. 10: Retreat of Loading Plate

[0338] The loading plate 120 externally retreats from the coarseadjustment stage 73, and movement of chuck Nos. 1 and 2 to the coarseadjustment stage 73 completes. The empty chuck B on the loading plate120 is unloaded by the chuck hand 123 to the coarse alignment unit 110.

[0339] No. 11: Reference Mark Measurement (Two Chucks)

[0340] On the measurement side, the measurement electrostaticcapacitance sensors S5 to S8 measure the upper surfaces of the chuckreference plates on chuck No. 2.

[0341] At the same time, the focus detection system 7 performs focusmeasurement. The electrostatic capacitance sensors S5 to S8 and focusdetection system 7 perform calibration. The alignment scope 5(simultaneous measurement at low and high magnifications) on themeasurement side measures the chuck reference marks 602 in the chuckreference plates 600 on chuck No. 2.

[0342] Though not shown, the two or more chuck reference marks 602 aremeasured.

[0343] On the exposure side, the exposure electrostatic capacitancesensors S1 to S4 measure the upper surfaces of the chuck referenceplates on chuck No. 1 in parallel with the above-mentioned operation.

[0344] The alignment scope (simultaneous measurement at low and highmagnifications) on the exposure side measures the chuck reference marks602 in the chuck reference plates 600 on chuck No. 1 to calculateinformation required for exposure.

[0345] No. 12: Focus Measurement and Exposure

[0346] The exposure unit starts exposure operation for wafer No. 1.

[0347] In parallel with this, the focus detection system 7 on themeasurement side performs focus measurement for entire upper surface ofchuck No. 2.

[0348] If an alignment shot comes to near a position where focusmeasurement is being performed by the alignment scope 5(high-magnification) on the measurement side, alignment measurement isalso performed for wafer No. 2, as shown in FIG. 14.

[0349] During this operation, chuck No. 3 is moved to the chuck loadingposition 121 of the loading plate 120, as shown in FIG. 17.

[0350] No. 13: Reference Mark Measurement (Two Chucks)

[0351] After the measurement, the alignment scopes (high-magnification)on the exposure and measurement sides measure the chuck reference marks602 in the chuck reference plates 600 on chuck Nos. 1 and 2.

[0352] It is confirmed whether the exposure and measurement operationscause any positional shift of the chucks.

[0353] (3) (Measurement of Third to (N−1)th Wafers) & (Exposure ofSecond to (N−2)th Wafers)

[0354] No. 14: Insertion of Loading Plate

[0355] The loading plate 120 is inserted. Then, the coarse adjustmentstage 73 moves to the unloading position (left rear) while the exposurefine adjustment stage 62 and measurement fine adjustment stage 72 arekept elevated, and the fine adjustment stages move downward. With thisoperation, chuck Nos. 1 and 2 are moved onto the loading plate 120.

[0356] No. 15: Movement of Coarse Adjustment Stage to Loading Position

[0357] After chuck Nos. 1 and 2 are passed to the loading plate 120, thecoarse adjustment stage 73 moves from the unloading position (left rear)to the loading position (left front).

[0358] At this position, the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move upward. Chuck No. 2 is coupledto the exposure fine adjustment stage 62 while chuck No. 3 holding thethird process wafer is coupled to the measurement fine adjustment stage72.

[0359] No. 16: Retreat of Loading Plate

[0360] The loading plate 120 externally retreats from the coarseadjustment stage 73, and movement of chuck Nos. 2 and 3 to the coarseadjustment stage 73 completes.

[0361] Chuck No. 1 having undergone exposure on the loading plate 120 isunloaded by the chuck hand 123 to the coarse alignment unit 110.

[0362] No. 17: Reference Mark Measurement (Two Chucks)

[0363] Reference mark measurement similar to that in No. 11 is performedfor chuck Nos. 3 and 2.

[0364] No. 18: Focus Measurement and Exposure

[0365] Focus measurement and exposure similar to that in No. 12 isperformed for chuck Nos. 3 and 2.

[0366] During this operation, chuck No. 4 is moved to the chuck loadingposition 121 of the loading plate 120, as shown in FIG. 18.

[0367] No. 19: Reference Mark Measurement (Two Chucks)

[0368] Reference mark measurement similar to that in No. 13 is performedfor chuck Nos. 3 and 2.

[0369] The above-mentioned operation is repeated until chuck No. Nholding the last process wafer is loaded onto the loading plate. Theprocesses to follow are obtained by incrementing the chuck number inNos. 14 to 19 by one.

[0370] (4) (Measurement of Nth Wafer) & (Exposure of (N−1)th Wafer)

[0371] No. 20: Insertion of Loading Plate

[0372] Chuck Nos. (N−2) and (N−1) are moved onto the loading plate 120.Basically, operation similar to that in No. 14 is performed.

[0373] No. 21: Movement of Coarse Adjustment Stage to Loading Position

[0374] After chuck Nos. (N−2) and (N−1) are passed to the loading plate120, the coarse adjustment stage 73 moves from the unloading position(left rear) to the loading position (left front).

[0375] At this position, the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move upward. Chuck No. (N−1) iscoupled to the exposure fine adjustment stage 62 while chuck No. Nholding the last process wafer is coupled to the measurement fineadjustment stage 72.

[0376] No. 22: Retreat of Loading Plate

[0377] The loading plate 120 externally retreats from the coarseadjustment stage 73, and the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move downward. Movement of chuckNos. (N−1) and N to the coarse adjustment stage 73 completes.

[0378] Chuck No. (N−2) having undergone exposure on the loading plate120 is unloaded by the chuck hand 123 to the coarse alignment unit 110.

[0379] No. 23: Reference Mark Measurement (Two Chucks)

[0380] Reference mark measurement similar to that in No. 11 is performedfor chuck Nos. N and (N−1).

[0381] No. 24: Focus Measurement and Exposure

[0382] Focus measurement and exposure similar to that in No. 12 isperformed for chuck Nos. N and (N−1).

[0383] During this operation, the empty chuck A is moved to the chuckloading position 121 of the loading plate 120, as shown in FIG. 18.

[0384] No. 25: Reference Mark Measurement (Two Chucks)

[0385] Reference mark measurement similar to that in No. 13 is performedfor chuck Nos. N and (N−1).

[0386] (5) Exposure of Nth Wafer

[0387] No. 26: Insertion of Loading Plate

[0388] Chuck Nos. (N−1) and N are moved onto the loading plate 120.Basically, operation similar to that in No. 14 is performed.

[0389] No. 27: Movement of Coarse Adjustment Stage to Loading Position

[0390] After chuck Nos. (N−1) and N are passed to the loading plate 120,the coarse adjustment stage 73 moves from the unloading position (leftrear) to the loading position (left front).

[0391] At this position, the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move upward. Chuck No. N is coupledto the exposure fine adjustment stage 62 while the empty chuck A iscoupled to the measurement fine adjustment stage 72.

[0392] No. 28: Retreat of Loading Plate

[0393] The loading plate 120 retreats, and the exposure fine adjustmentstage 62 and measurement fine adjustment stage 72 move downward.Movement of chuck No. N and empty chuck A to the coarse adjustment stage73 completes.

[0394] Chuck No. (N−1) having undergone exposure on the loading plate120 is unloaded by the chuck hand 123 to the coarse alignment unit 110.

[0395] No. 29: Reference Mark Measurement (on Exposure Side)

[0396] The measurement side bearing the empty chuck does not performmeasurement. Only measurement of the chuck reference marks 602 in thechuck reference plates 600 on chuck No. N is performed by the alignmentscope 650.

[0397] No. 30: Exposure

[0398] Exposure of chuck No. N starts. The measurement side bearing theempty chuck does not perform focus measurement and the like.

[0399] During this operation, the empty chuck B is moved to the chuckloading position 121 of the loading plate 120, as shown in FIG. 19.

[0400] (6) End Process

[0401] No. 31: Insertion of Loading Plate

[0402] Chuck No. N and the empty chuck A are moved onto the loadingplate 120.

[0403] No. 32: Movement of Coarse Adjustment Stage to Loading Position

[0404] After chuck No. N and the empty chuck A are passed to the loadingplate 120, the coarse adjustment stage 73 moves from the unloadingposition (left rear) to the loading position (left front).

[0405] At this position, the exposure fine adjustment stage 62 andmeasurement fine adjustment stage 72 move upward. The empty chuck A iscoupled to the exposure fine adjustment stage 62 while the empty chuck Bis coupled to the measurement fine adjustment stage 72.

[0406] No. 33: Retreat of Loading Plate

[0407] The loading plate 120 retreats, and the exposure fine adjustmentstage 62 and measurement fine adjustment stage 72 move downward.Movement of the empty chucks A and B to the coarse adjustment stage 73completes.

[0408] Chuck No. N having undergone the last exposure on the loadingplate 120 is unloaded by the chuck hand 123 to the coarse alignment unit110.

[0409] No. 34: Movement of Coarse Adjustment Stage to Unloading Position

[0410] The coarse adjustment stage .73 is moved to the unloadingposition, and the entire wafer process ends.

[0411] Operation that pertains to the coarse adjustment stage has beendescribed. In the semiconductor exposure apparatus of this embodiment,both the exposure fine adjustment stage 62 and the measurement fineadjustment stage 72 on the coarse adjustment stage 73 have respectivechucks. The coarse adjustment stage is driven only when the chucks arenot mounted on the fine adjustment stages. This aims at keeping theweight balance of the coarse adjustment stage constant and maintainingthe stable stage performance in high-speed driving.

[0412] [Outline of Chuck Unloading Function (FIG. 21)]

[0413]FIG. 21 shows how a chuck is unloaded. In FIG. 21, referencenumeral 700 denotes a chuck cassette which can accommodate a pluralityof chucks.

[0414] The semiconductor exposure apparatus of this embodiment insertsthe hand unit of the unloading hand 131 into the chuck support unit 412below the chuck 405 and unload the chuck 405 from the coarse chuck stage113 to the unloading load-lock chamber 130 at the wafer unloadingposition of the coarse alignment unit 110.

[0415] The chuck 405 having been unloaded to the unloading load-lockchamber 130 is accommodated by the wafer hand 102 in the chuck cassette700, similarly to a wafer.

[0416]FIG. 21 shows unloading operation. Chuck loading operation can beperformed in reverse order to that shown in FIG. 21 in inverse order.

[0417] [Modification]

[0418] As modifications of the semiconductor exposure apparatusaccording to the embodiment of the present invention, the followingsemiconductor exposure apparatuses can readily be devised:

[0419] 1. a semiconductor exposure apparatus which uses two chucks;

[0420] 2. a semiconductor exposure apparatus which uses four or morechucks, further divides each process in transport and prealignment unitsinto smaller processes, and performs the processes in parallel;

[0421] 3. a semiconductor exposure apparatus which uses a hand to move achuck from a loading position to the first stage, to move from the firststage to the second stage, and to move from the second stage to anunloading position;

[0422] 4. a semiconductor exposure apparatus which measures the heightof chuck reference plates and that of a wafer by the same sensor; and

[0423] 5. a semiconductor exposure apparatus in which each measurementfine adjustment stage is fixed to perform measurements whose measurementranges are wide by focus measurement and alignment systems.

[0424] In this case, each measurement system needs to increase themeasurement range while maintaining the measurement precision. On theother hand, no interference occurs between two fine adjustment stagesdue to vibrations.

[0425] As has been described above, according to this embodiment, forexample, two fine adjustment stages are arranged on one coarseadjustment stage, and part of exposure, focus measurement, and alignmentmeasurement can be performed simultaneously at exposure and measurementpositions by operation of the one coarse adjustment stage. This makes itpossible to implement a small high-speed exposure apparatus.

[0426] A wafer having undergone measurement on the measurement fineadjustment stage on the one coarse adjustment stage only needs to moveonto the adjacent exposure fine adjustment stage. This prevents anypositional shift of the wafer after the measurement from a chuck andimplements more accurate alignment/focus at the exposure position.

[0427] Since a large focus detection system for wafer measurement isspaced apart from below a projection system, this embodiment can produceadditional effects. More specifically, constraints on mounting space arerelaxed for the focus detection system for wafer measurement. This makesit much easier to improve and maintain the focus detection system forwafer measurement.

[0428] In addition, since the focus measurement system need not bearranged below the projection system, constraints on the design of theprojection system are relaxed.

[0429] A chuck unloading mechanism according to this embodiment caneasily and automatically unload or load the chuck to or from the outerair side even when its exposure space is purged with nitrogen orevacuated to a vacuum. This largely shortens a maintenance time andmakes it possible to maintain the cleanliness of the space.

[0430] [Other Embodiment]

[0431] The present invention includes a case wherein the invention isachieved by directly or remotely supplying a program of software thatimplements a control flow for measurement and exposure operations of theaforementioned embodiment to a system or apparatus, and reading out andexecuting the supplied program code by a computer of that system orapparatus. In this case, software need not have the form of program aslong as it has the program function.

[0432] Therefore, the program code itself installed in a computer toimplement the functional process of the present invention using thecomputer implements the present invention. That is, the scope of theclaims of the present invention includes the computer program itself forimplementing the functional process of the present invention.

[0433] In this case, the form of program is not particularly limited,and an object code, a program to be executed by an interpreter, scriptdata to be supplied to an OS, and the like may be used as along as theyhave the program function.

[0434] As a recording medium for supplying the program, for example, aflexible disk, hard disk, optical disk, magnetooptical disk, MO, CD-ROM,CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM,DVD-R), and the like may be used.

[0435] As another program supply method, the program may be supplied byestablishing connection to a home page on the Internet using a browseron a client computer, and downloading the computer program itself of thepresent invention or a compressed file containing an automaticinstallation function from the home page onto a recording medium such asa hard disk or the like. Also, the program code that forms the programof the present invention may be segmented into a plurality of files,which may be downloaded from different home pages. That is, the scope ofthe claims of the present invention includes a WWW server which makes aplurality of users download a program file required to implement thefunctional process of the present invention by the computer.

[0436] Also, a storage medium such as a CD-ROM or the like, which storesthe encrypted program of the present invention, may be delivered to theuser, the user who has cleared a predetermined condition may be allowedto download key information that decrypts the program from a home pagevia the Internet, and the encrypted program may be executed using thatkey information to be installed on a computer, thus implementing thepresent invention.

[0437] The functions of the aforementioned embodiment may be implementednot only by executing the readout program code by the computer but alsoby some or all of actual processing operations executed by an OS or thelike running on the computer on the basis of an instruction of thatprogram.

[0438] Furthermore, the functions of the aforementioned embodiment maybe implemented by some or all of actual processes executed on the basisof an instruction of that program by a CPU or the like arranged in afunction extension board or a function extension unit, which is insertedin or connected to the computer, after the program read out from therecording medium is written in a memory of the extension board or unit.

[0439] As many apparently widely different embodiments of the presentinvention can be made without departing from the spirit and scopethereof, it is to be understood that the invention is not limited to thespecific embodiments thereof except as defined in the appended claims.

What is claimed is:
 1. An exposure apparatus which exposes substrates toa pattern on a master, comprising: first, second, and third chucks whichhold the substrates; a first fine adjustment stage which holds saidfirst chuck to perform fine driving; a second fine adjustment stagewhich holds said second chuck to perform fine driving; a coarseadjustment stage on which said first and second fine adjustment stagesare mounted and which can move in an X-Y plane substantiallyperpendicular to an optical axis; an exposure unit which performsexposure operation for the substrate held by said first chuck; ameasurement unit which performs measurement operation for the substrateheld by said second chuck; and a controller which drives said coarseadjustment stage and causes said measurement and exposure units toperform the measurement and exposure operations, respectively, whereinsaid controller performs in parallel the measurement and exposureoperations for the substrates by serially performing an operation ofunloading the substrate having undergone the exposure operation togetherwith said first chuck from said first fine adjustment stage, anoperation of moving the substrate having undergone the measurementoperation from said second fine adjustment stage to said first fineadjustment stage while the substrate is held by said second chuck, andan operation of loading a substrate to be subjected to the measurementoperation next while the substrate is held by said third chuck.
 2. Theapparatus according to claim 1, wherein said first chuck also serves assaid third chuck.
 3. The apparatus according to claim 1, furthercomprising a chuck in addition to said first to third chucks.
 4. Theapparatus according to claim 1, wherein the master and substrates arebrought into a stationary state during the exposure operation.
 5. Theapparatus according to claim 1, wherein the master and substrates arescanned during the exposure operation.
 6. The apparatus according toclaim 1, further comprising a chuck holding mechanism which temporarilyholds said first and second chucks outside said coarse adjustment stage,wherein unloading of said first chuck from said first fine adjustmentstage and movement of said second chuck from said second fine adjustmentstage to said first fine adjustment stage are performed in parallel bytemporarily moving said first chuck which holds the substrate havingundergone the exposure operation and second chuck which holds thesubstrate having undergone the measurement operation from said coarseadjustment stage to said chuck holding mechanism, moving said coarseadjustment stage separated from said first and second chucks, andreturning said second chuck to said coarse adjustment stage.
 7. Theapparatus according to claim 1, further comprising a chuck holdingmechanism which temporarily holds said first, second, and third chucksoutside said coarse adjustment stage, wherein unloading of said firstchuck from said first fine adjustment stage, movement of said secondchuck from said second fine adjustment stage to said first fineadjustment stage, and loading of said third chuck to said second fineadjustment stage are performed in parallel by temporarily moving saidfirst chuck which holds the substrate having undergone the exposureoperation and second chuck which holds the substrate having undergonethe measurement operation from said coarse adjustment stage to saidchuck holding mechanism, moving said coarse adjustment stage separatedfrom said first and second chucks, and returning said second and thirdchucks to said coarse adjustment stage.
 8. The apparatus according toclaim 1, wherein at least one reference plane for a height direction isarranged on an edge of each of said chucks which hold the substrates, afirst sensor which measures the reference plane in the height directionis arranged below a projection system of said exposure unit, a secondsensor which measures the reference plane in the height direction and athird sensor which measures the substrate in the height direction arearranged below said measurement unit, said measurement unit measures aheight of the reference plate by the second sensor and measures a heightat each position in the X-Y plane of the substrate by the third sensor,and said exposure unit measures the reference plane in the heightdirection by the first sensor, then calculates each position in the X-Yplane of the substrate from measurement results of the height of thereference plane and the height at each position in the X-Y plane of thesubstrate obtained in advance by the second and third sensors in saidmeasurement unit and a measurement result by the first sensor, andperforms the exposure operation by driving in the height direction orthe height direction and a tilt direction of the substrate such thateach exposure region on the substrate coincides with a position of animage plane of the projection system.
 9. The apparatus according toclaim 8, wherein measurement of the height at each position in the X-Yplane of the substrate by the third sensor in said measurement unit, andexposure operation for the substrate having undergone measurement insaid exposure unit are performed in parallel.
 10. The apparatusaccording to claim 8, wherein measurement of a reference plane on saidfirst chuck by the first sensor and measurement of a reference plane onsaid second chuck by the second sensor are performed in parallel. 11.The apparatus according to claim 8, wherein calibration of thesecond-and third sensors is executed by simultaneously performingmeasurement of a reference plane on said second chuck by the secondsensor and measurement of the reference plane on said second chuck bythe third sensor.
 12. The apparatus according to claim 8, wherein thesecond sensor measures the reference plane and the substrate in theheight direction, and the third sensor can be removed.
 13. The apparatusaccording to claim 8, wherein said first and second sensors are of thesame type.
 14. The apparatus according to claim 8, wherein the first andsecond sensors are of an electrostatic capacitance type.
 15. Theapparatus according to claim 8, wherein the third sensor comprises aprojection unit which projects a specific mark onto a substrate byoblique incidence and a detection unit which image-senses the specificmark.
 16. The apparatus according to claim 1, wherein at least onereference mark for X and Y directions is arranged on an edge of each ofsaid chucks which hold the substrates, a first alignment unit whichmeasures the reference mark in the X and Y directions is arranged insaid exposure unit, a second alignment unit which measures the referencemark and alignment marks for measurement shots on each substrate in theX and Y directions is arranged in said measurement unit, saidmeasurement unit measures the reference mark in the X and Y directionsand a position of the alignment marks for the measurement shots in the Xand Y directions by the second alignment unit, and said exposure unitmeasures the reference mark in the X and Y directions by the firstalignment unit, calculates an alignment error at each position of thesubstrate from measurement results of the reference mark and eachposition in the X and Y directions of the substrate obtained in advanceby the second alignment unit in said measurement unit and a measurementresult of the reference mark by the first alignment unit, and performsthe exposure operation by correcting the error such that the substrateis exposed to the pattern on the master at a predetermined position. 17.The apparatus according to claim 16, wherein the measurement of theposition of the alignment marks for the measurement shots on thesubstrate by the second alignment unit is performed in parallel with theexposure operation or by temporarily interrupting the exposure operationwhen the second alignment unit comes to near the measurement shot duringthe exposure operation for the substrate by said exposure unit.
 18. Theapparatus according to claim 17, wherein said coarse adjustment stage isdriven such that a Y-direction speed in turning operation becomes zeroat a Y-coordinate of the position of the alignment mark for themeasurement shot and is temporarily stopped such that a X-directionspeed becomes zero at an X-coordinate of the position of the alignmentmark for the measurement shot.
 19. The apparatus according to claim 16,wherein the measurement of the reference mark in the X and Y directionson said first chuck by the first alignment unit and the measurement ofthe reference mark on said second chuck by the second alignment unit areperformed in parallel.
 20. The apparatus according to claim 16, whereinthe first alignment unit can perform simultaneous measurement at highand low magnifications, performs the simultaneous measurement at thehigh and low magnifications for the reference mark on said first chuck,performs position measurement for the reference mark if the referencemark falls within a high-magnification measurement range, and performsposition measurement for the reference mark by driving said firstadjustment stage or said first adjustment stage and coarse adjustmentstage on the basis of a measurement result of the low magnification tomove the reference mark to the high-magnification measurement range ifthe reference mark falls outside the high-magnification measurementrange.
 21. The apparatus according to claim 16, wherein the secondalignment unit can perform simultaneous measurement at high and lowmagnifications, performs the simultaneous measurement at the high andlow magnifications for the reference mark on said second chuck, performsposition measurement for the reference mark if the reference mark fallswithin a high-magnification measurement range, and performs positionmeasurement for the reference mark by driving said second adjustmentstage or said second adjustment stage and coarse adjustment stage on thebasis of a measurement result of the low magnification to move thereference mark to the high-magnification measurement range if thereference mark falls outside the high-magnification measurement range.22. The apparatus according to claim 1, wherein a position of a chuckreference mark on each of said chucks and a position of an alignmentmark on the substrate held on said chuck are measured before loadingsaid chuck to said coarse adjustment stage, and said chuck is loaded tosaid coarse adjustment stage such that the chuck reference mark and saidcoarse adjustment stage have a predetermined positional relationship.23. The apparatus according to claim 1, wherein a position of a chuckreference mark on each of said chucks and a position of an alignmentmark on the substrate held on said chuck are measured before loadingsaid chuck to said coarse adjustment stage, and relative alignment ofsaid chuck with the substrate is performed such that the alignment markand the chuck reference mark have a predetermined relative positionalrelationship.
 24. The apparatus according to claim 1, wherein a heightof a chuck reference mark on each of said chucks and heights at aplurality of positions in X and Y directions of the substrate held onsaid chuck are measured before loading said chuck to said coarseadjustment stage, and after said chuck is loaded to said second fineadjustment stage, said chuck is driven in height and tilt directions bysaid second fine adjustment stage on the basis of a measurement resultsuch that the height of the chuck reference mark and the heights of thesubstrate fall within measurement ranges of second and third sensors.25. The apparatus according to claim 1, wherein a driving stroke of saidsecond fine adjustment stage is set to be longer than a driving strokeof said first fine adjustment stage.
 26. The apparatus according toclaim 1, wherein said first and second fine adjustment stages havedifferent mechanical resonance frequencies.
 27. The apparatus accordingto claim 1, wherein control parameters for said first and second fineadjustment stages in exposure operation by said exposure unit are madeto differ from control parameters for said first and second fineadjustment stages in measurement operation, to be performed during theexposure operation, for a position of an alignment mark for ameasurement shot on each of the substrates by said measurement unit. 28.The apparatus according to claim 1, wherein a bar mirror is provided ineach of said first and second fine adjustment stages to enable positionmeasurement in X and Y directions by a laser interferometer of saidcoarse adjustment stage, and a relative error in the X direction and arelative error in the Y direction of each bar mirror of said first andsecond fine adjustment stages can be measured by driving said coarseadjustment stage in the X and Y directions while at least one of saidfirst and second fine adjustment stages is fixed with respect to saidcoarse adjustment stage.
 29. The apparatus according to claim 1, whereina plurality of projections are formed in each of upper surfaces of topplates of said first and second fine adjustment stages.
 30. Theapparatus according to claim 1, wherein said coarse adjustment stage isdriven at a high speed when said first and second fine adjustment stageseach have a chuck or when said first and second fine adjustment stageshave no chucks.
 31. The apparatus according to claim 1, wherein a chuckis held on each of said first and second fine adjustment stages, and atleast one chuck is provided outside said coarse adjustment stage in theexposure and measurement operations, and each of the chucks outside saidcoarse adjustment stage performs all or some of unloading of a substratefrom the chuck, loading of a substrate to be processed next, measurementof a height of a chuck reference plane, measurement of a position of achuck reference mark, measurement of a height of the substrate,measurement of a position of an alignment mark on the substrate, andrelative alignment of the alignment mark on the substrate with the chuckreference mark, in parallel with the exposure and measurement operationson said coarse adjustment stage.
 32. The apparatus according to claim 1,wherein said chucks circulate and move through a clean air space, anitrogen-purged space, or a vacuum space, a substrate having undergoneexposure is detached from the corresponding chuck at an unloadingposition of the space and is unloaded from the space to an outer airside, and a substrate to be exposed is loaded at a loading position ofthe space from the outer air side to the corresponding chuck.
 33. Theapparatus according to claim 1, wherein both unloading of a substratefrom a chuck in the clean air space, nitrogen-purged space, and vacuumspace and unloading of a chuck from the space are performed by the sameunloading unit.
 34. The apparatus according to claim 1, wherein aposition of a chuck reference mark is measured again after the exposureoperation in said exposure unit or the measurement operation in saidmeasurement unit, and cleaning of top plates of said fine adjustmentstages, issuance of a warning, or abnormal stop is performed when ameasurement result exceeds a predetermined amount.
 35. An exposureapparatus which exposes substrates to a pattern on a master through aprojection system, comprising: first, second, and third chucks whichhold the substrates; a fine adjustment stage which holds said firstchuck to perform fine driving; a chuck holding unit which holds saidsecond chuck; a coarse adjustment stage on which said fine adjustmentstage and chuck holding unit are mounted and which can move in an X-Yplane substantially perpendicular to an optical axis of the projectionsystem; an exposure unit which performs exposure operation for thesubstrate held by said first chuck; a measurement unit which performsmeasurement operation for the substrate held by said second chuck; and acontroller which drives said coarse adjustment stage and causes saidmeasurement and exposure units to perform the measurement and exposureoperations, respectively, wherein said controller performs in parallelthe measurement and exposure operations for the substrates by seriallyperforming an operation of unloading the substrate having undergone theexposure operation together with said first chuck from said fineadjustment stage, an operation of moving the substrate having undergonethe measurement operation from said chuck holding unit to said fineadjustment stage while the substrate is held by said second chuck, andan operation of loading the substrate to be subjected to the measurementoperation next to said chuck holding unit while the substrate is held bysaid third chuck.
 36. The apparatus according to claim 35, wherein saidfirst chuck also serves as said third chuck.
 37. The apparatus accordingto claim 35, further comprising a chuck in addition to said first tothird chucks.
 38. An exposure method in an exposure apparatus whichcomprises first, second, and third chucks which hold substrates, a firstfine adjustment stage which holds the first chuck to perform finedriving, a second fine adjustment stage which holds the second chuck toperform fine driving, a coarse adjustment stage on which the first andsecond fine adjustment stages are mounted and which can move in an X-Yplane substantially perpendicular to an optical axis, an exposure unitwhich performs exposure operation for the substrate held by the firstchuck, a measurement unit which performs measurement operation for thesubstrate held by the second chuck, and a controller which drives thecoarse adjustment stage and causes the measurement and exposure units toperform in parallel the measurement and exposure operations,respectively, and exposes the substrates to a pattern on a master,comprising: a step of unloading the substrate having undergone theexposure operation together with the first chuck from the first fineadjustment stage; a step of moving the substrate having undergone themeasurement operation from the second fine adjustment stage to the firstfine adjustment stage while the substrate is held by the second chuck,and a step of loading a substrate to be subjected to the measurementoperation next while the substrate is held by the third chuck.
 39. Anexposure apparatus which exposes substrates to a pattern on a master,comprising: a plurality of fine adjustment stages which hold chucksholding the substrates to perform fine driving; a coarse adjustmentstage on which said plurality of fine adjustment stages are mounted andwhich can move in an X-Y plane substantially perpendicular to an opticalaxis; exposure means for performing exposure operation for each of thesubstrates held by the chucks; measurement means for performingmeasurement operation for each of the substrates held by the chucks; andcontrol means for driving said coarse adjustment stage and causing saidmeasurement and exposure means to perform in parallel the measurementand exposure operations, respectively.